AN 

ELEMENTARY  PHYSIOLOGY 
AND  HYGIENE 

FOR    USE  IN  UPPER   GRAMMAR   GRADES 


BY 
H.  W.  CONN,  PH.D. 

t  i 

PROFESSOR   OF  BIOLOGY   IN   WESLEYAN   UNIVERSITY 

THE   PUBLIC   HEALTH   AND    THE   CITIZEN 


SILVER,   BURDETT  AND   COMPANY 

NEW  YORK  BOSTON  CHICAGO 


COPYRIGHT,  1903,  1906,  1910, 
BY  SILVER,  BURDETT  AND  COMPANY 


OF   THE 

UNIVERSITY 

OF 


PREFACE 

THE  aim  of  the  author  in  writing  the  present  work 
has  been  to  furnish  an  elementary  text-book  in  physi- 
ology and  hygiene  which  should  recognize  some  of  the 
more  important  discoveries  of  recent  years  concerning 
matters  pertaining  to  health,  and  which  should  also 
attempt  to  exemplify  in  the  clearest  way  the  inter- 
relation between  physiology  and  hygiene. 

The  primary  object  of  the  study  of  physiology  in  our 
schools  is  to  inculcate  an  intelligent  care  of  the  body. 
With  this  in  view,  matters  of  hygiene  must  in  one 
sense  take  first  place,  although  our  understanding  of 
hygiene  must  be  based  upon  a  knowledge  of  physi- 
ology. In  the  present  work  the  study  of  the  body,  of 
its  various  parts  and  their  functions,  is  given  full  and 
comprehensive  treatment;  at  the  same  time  lessons  on 
hygiene  are  given  as  natural  results  of  the  principles 
of  physiology  and  as  closely  related  thereto. 

A  knowledge  of  foods  and  their  values  and  of  the 
causes  and  distribution  of  contagious  and  other  germ 
diseases  is  of  vital  importance  to  every  boy  and  girl. 

The  effect  of  alcohol  upon  the  various  functions  of 
the  body  is  treated  throughout  the  book  in  direct  rela- 
tion with  the  particular  organs  or  functions  concerned. 
The  dangers  connected  with  the  use  of  alcohol  will  be 
found  plainly  indicated  in  accord  with  the  results  of  the 
latest  investigations  in  that  department  of  science. 

8 

205690 


4  PREFACE 

The  author  desires  to  express  his  hearty  acknowledg- 
ments to  Superintendent  W.  P.  Ferguson  of  Middle- 
town  and  Dr.  George  W.  Fitz  of  Boston  for  their 
kindness  in  looking  over  the  proofs  of  the  work  and 
giving  him  the  benefit  of  their  criticisms.  He  wishes 
also  to  express  his  obligations  to  Professor  W.  O.  At- 
water,  Professor  William  N".  Rice,  and  Dr.  F.  G.  Bene- 
dict of  Wesley  an  University,  to  Professor  C.  F.  Hodge 
of  Clark  University,  totheEev.  J.  H.  James,  President 
of  the  Connecticut  Temperance  Union,  and  to  Superin- 
tendent J.  G.  Edgerly  of  Fitchburg,  Massachusetts,  for 
their  valuable  suggestions.  While  acknowledging  ob- 
ligations to  these  gentlemen,  it  is  not  implied  that  any 
of  them  can  be  held  responsible  for  the  method  of  treat- 
ment in  the  work  or  as  necessarily  indorsing  it. 

In  connection  with  this  new  edition  the  author  de- 
sires to  call  particular  attention  to  the  new  chapter  01 
Preventable  Diseases,  and  the  enlarged  discussions  oi 
the  subjects  of  Public  Hygiene  and  Emergencies.  Il 
is  hoped  that  the  presentation  of  these  subjects  wilj 
help  to  make  the  young  citizen  an  intelligent  am 
efficient  member  of  the  community  in  matters  thaj 
pertain  to  the  public  health. 


CONTENTS 


CHAPTER 

I.    FOODS  AND  DRINKS      . 
Purposes  of  Food 
Kinds  of  Food 
Sources  of  Food 
Other  Food  Material 

II.    DIGESTION    . 
The  Mouth 
Food  in  the  Mouth  and 

Throat 

Food  in  the  Stomach 
Food  in  the  Intestines 


PAGE 

11-36 


Alcohol 

Amount  of  Food  Needed 

Comparative  Food  Values 

37-64 

Digestibility  of  Foods 
How  the  Food  gets  into 

the  Blood 
Undigested     Portions     of 

the  Food 


III.  FOOD  HABITS  AND  COOKING  .... 
Proper  Habits  of  Eating  Purposes  of  Cooking 
The  Habit  of  using  Alco-  Principles  of  Cooking 


65-79 


hoi 

IV.    CIRCULATION 
The  Blood 
What  makes  the   Blood 

Flow 

Blood  Vessels 
How  the  Blood  Flows 

V.    RESPIRATION 

The  Air  Passages  and  the 

Lungs 
How  Air  is  drawn  into 

the  Lungs 


Methods  of  Cooking 

80-103 

How  the  Flow  of  Blood  is 

Controlled 

Summary  of   the   Circula- 
tion Process 


104-123 

What  Breathing  does  for 

the  Blood 
Ventilation 
How  to  restore  Respiration 


6  CONTENTS 

CHAPTER  PAGE 

VI.     THE  FRAMEWORK  AND  MOTION  OF  THE  BODY     124-152 

The  Skeleton  Joints 

The  Bones  The  Muscles 

Cartilage 

VII.     THE  KIDNEYS  AND  THE  SKIN  AND  THEIR  DUTIES   153-171 

Waste  Products  The  Skin 

The  Kidneys  Functions  of  the  Skin 

VIII.    THE  CARE  OF  THE  SKIN 172-179 

Bathing  Burns 

Clothing  Frostbites 

IX.     ALCOHOL  AND  OTHER  NARCOTICS     .        .        .      180-188 
Opium  Alcohol 

Tobacco 

X.     THE  NERVOUS  SYSTEM 189-197 

The  Brain  The  Nerves 

The  Spinal  Cord 

XL    THE  NERVOUS  SYSTEM  IN  ACTION    .        .        .     198-212 
Duties  of  the  Nerves  The  Cerebellum  and  Cerebrum 

Duties  of  the  Spinal  Cord     The  Importance  of  Habits 
and  Medulla  The  Care  of  the  Mind 

XII.    THE  SENSES 213-236 

The  Sense  of  Sight  The  Sense  of  Smell 

The  Sense  of  Sound  Skin  Sensations 

The  Sense  of  Taste 

XIII.    HEALTH  AND  DISEASE 237-251 

Parasitic  Diseases  The    Duty    of    preserving 

The  Use  of  Alcohol  Health 

XTV.     PREVENTABLE  DISEASES 252-270 

Germ  Diseases  Preventable  Diseases  of  the  Blood 

Source  of  Disease  Germs  Skin  Eruptions 

Diseases  of  the  Mouth  and  Preventable  Diseases 

Respiratory  Organs  Immunity   against   Germ 

Diseases  of  the  Digestive  Diseases 

Organs 


CONTENTS 


CHAPTER 

XV. 


A  WAR  FOR  THE  NATION       ....     277-290 

Consumption  not    He-    How  to  Combat  Bacteria 

reditary  Alcohol  and  Consumption 

Consumption  can     be     Precautions  for  Consump- 

Prevented  tives 

Consumption  can     be     Food  and  Exercise 

Cured  Animal  Tuberculosis 


XVI. 


PUBLIC  HYGIENE 
Boards  of  Health 
Water 
Fresh  Air 


.      291-301 
Foods 

Garbage  and  Sewage 
Protection  from  Contagious 
Diseases 


XVII. 


305-315 


WHAT  TO  DO  IN  EMERGENCIES 

Various  Diseases  Sunstroke 

Accidents  Poisons 

Bites    of    Insects    and 
Snakes 


XVIII.   How  TO  DEVELOP  OUR  BODIES        .        .        .     316-332 
Breathing  Exercises  to  Develop  Vari- 

Walking  ous  Parts  of  the  Body 

Games  and  Sports 
Alcohol  and  Athletics 


Exercises  for  Suppleness 
— Ease  of  Motion 


GLOSSARY 
INDEX 


333-341 
342-349 


ILLUSTRATIONS 


1.  Starch  Grains 16 

2.  Fat  Cells 17 

3.  A  Small  Bit  of  a  Grain  of  Wheat     .....  21 

4.  The  Oat  Plant .         .22 

5.  A  Small  Bit  of  Potato 23 

6.  Yeast  Plant 27 

7.  Sugar  Solution  undergoing  Fermentation  by  Yeast          .  28 

8.  Showing  the  Proportion  of  Alcohol  and  Water  in  Beer, 

Wine,  and  Whisky       . 29 

9.  The  Upper  Teeth .  39 

10.  The  Mouth 40 

11.  A  Diagram  of  the  Side  of  the  Face 41 

12.  A  Section  through  the  Head      ......  44 

13.  The  Digestive  Organs  of  the  Abdomen     ....  47 

14.  A  Section  of  the  Wall  of  the  Stomach      ....  48 

15.  Showing  the  Location  of  the  Digestive  Organs         .        .  50 

16.  A  Bit  of  the  Intestine 58 

17.  A  Bit  of  the  Intestine 59 

18.  A  Single  Villus 60 

19.  A  Simple  Device  for  showing   how  Foods  may  pass 

through  Membranes 61 

20.  A  Little  Blood  as  it  appears  under  a  Microscope      .        .  81 

21.  The  Heart 83 

22.  A.  The  Chief  Arteries  and  Veins.      B.  Showing  the 

Entrance  of  the  Chief  Veins  into  the  Heart      facing  84 

23.  The  Right  Side  of  the  Heart 84 

24.  The  Left  Side  of  the  Heart 84 

25.  Capillaries 88 

26.  Diagram  showing  General  Circulation      ....  89 

27.  Showing  Main  Artery  of  the  Arm    ,        .        .        •        .91 

8 


ILLUSTRATIONS 


28.  Showing  Main  Artery  in  the  Leg 91 

29.  Showing  how  to  compress  the  Arm  to  stop  Bleeding       .  92 

30.  Showing  the  Method  of  applying  a  Ligature    ...  93 

31.  Showing  the  Clotting  of  Blood 94 

32.  Section  of  an  Artery  and  a  Vein       .....  98 

33.  The  Lungs 107 

34.  Air  Sacs 108 

35.  The  Air  Sac  of  the  Lungs          ....       facing  108 

36.  Muscle  Fibers facing  108 

37.  Showing  Chest  with  Lungs  and  Heart  behind  the  Ribs  .  109 

38.  Showing  Movement  of  the  Diaphragm  in  Breathing        .  110 

39.  Showing  Movement  of  the  Ribs  in  Breathing  .        .        .  Ill 

40.  Ventilation 119 

41.  The  Method  of  Moving  the  Arms  to  produce  Artificial 

Breathing 121 

42.  The  Human  Skeleton         ...  ...  125 

43.  Two  Vertebrae  in  Position 126 

44.  The  Human  Skull 127 

45.  A  Section  of  the  Femur    *        ......  128 

46.  The  Cramped  Foot 130 

47.  The  Uncramped  Foot 130 

48.  An  Improperly  Shaped  Shoe 131 

49.  The  Properly  Shaped  Shoe 131 

50.  Two  Vertebrae    .........  133 

51.  The  Bones  forming  the  Knee  Joint 135 

52.  The  Knee  Joint          .        . 136 

53.  The  Bones  of  the  Shoulder  Joint "138 

54.  The  Shoulder  Joint 139 

55.  Showing  Method  of  Attachment  of  Biceps  Muscle  to 

move  the  Forearm        .......  141 

56.  Showing  Muscles  and  Tendons  of  the  Arm       .        .        .  142 

57.  A  Bit  of  Muscle         .        .   '  ' 143 

58.  A  Bit  of  Muscle 143 

59.  The  Surface  Muscles  of  the  Body 147 

60.  The  Kidneys .155 

61.  A  Section  of  a  Bit  of  Skin        ....  ,157 

62.  A  Hair 159 

63.  A  Section  through  the  Tip  of  the  Finger         .        .        .161 


10  ILLUSTRATIONS 

FIG.  PAGE 

64.  A  Bit  of  Skin  as  it  appears  under  a  Microscope       .        .  164 

65.  The  Human  Brain 190 

66.  The  Nervous  System 192 

67.  Two  Pieces  of  the  Spinal  Cord 193 

68.  A  Nerve 195 

69.  A  Nerve  Cell 19(5 

70.  Showing  Connection  of  Hand  with  Brain  by  a  Nerve      .  199 

71.  The  Brain  in  Position 206 

72.  The  Eye,  viewed  from  in  Front         .....  214 

73.  The  Eye,  viewed  from  the  Side 216 

74.  A  Comparison  of  the  Structure  of  a  Camera  and  the  Eye  217 

75.  A  Diagram  representing  a  Section  through  the  Human 

Eye 218 

76.  The  Ear 222 

77.  The  Tongue 227 

78.  A  Vertical  Section  of  the  Nose 230 

79.  Bacteria  that  Produce  Certain  Diseases  ....  240 

80.  81.    Comparative  Diagrams       .....      253,  254 

82.  The  Common  House  Fly 262 

83.  The  Hook  Worm 263 

84.  85.    Anopheles  and  Culex 

86,   87.    Stegornyia  and  the  Flea 

88.  The  Rat 

89.  Diagram  comparing  the  Deaths  due  to  Four  Years  of 

Civil  War  and  Four  Years  of  Tuberculosis  .         .         .  278 

90.  A  Sleeping  Veranda  at  a  Consumptives'  Home         .         .  283 

91.  The  Sun  Parlor  of  a  Large  Hospital          .         .         .         .281 

92.  A  Well  Properly  located 293 

93.  An  Unhealthful  Location  for  a  Well         ....  294 

94.  Diagram  of  Connections  with  City  Sewers        .         .         .  29S 

95.  96,  97.    A  Bumble  Bee,  a  Wasp,  and  a  Honey  Bee  .         .  308 

98.  The  Leaves  of  the  Woodbine  and  Poison  Ivy  .         .         .310 

99,  100.   Illustrating  Exercises  1  and  2 323 

101.  Illustrating  Exercise  4 325 

102,  103,  104.    Illustrating  Exercises  5,  7,  and  8    ...  326 
105,  106.    Illustrating  Exercises  18  and  19      ....  329 
107,  108.   Illustrating  Exercises  20  and  21      .         .        .         .  330 
109.    Hammer  Throwing .         . 331 


PHYSIOLOGY   AND   HYGIENE 

CHAPTER   I 
FOODS   AND    DRINKS 

OUR  bodies  are  in  some  respects  like  an  engine 
that  is  constantly  at  work.  As  an  engine  is  cold  and 
powerless  without  fuel,  so  our  bodies  without  food 
would  starve  and  die.  As  the  engine  usually  works 
smoothly  and  strongly,  so  the  body,  when  we  are  in 
good  health,  is  strong  and  active.  But  sometimes  the 
body,  like  the  engine,  breaks  down  in  part,  and  cannot 
do  all  its  work.  Then  we  say  that  we  are  ill.  Smooth 
action  of  the  engine  means  good  health.  When  any- 
thing interferes  with  its  working  properly,  sickness 
results.  If  the  machine  stops  entirely,  we  say  there  is 
death.  Physiology  teaches  us  about  the  body,  what 
the  work  of  each  part  is;  and  Hygiene  teaches  us  how  we 
may  treat  the  body  wisely,  just  as  the  skillful  engineer 
cares  for  his  engine  in  the  best  possible  way. 

PURPOSES  OF  FOOD 

When  we  speak  of  food,  we  ordinarily  mean  materials 
suitable  for  us  to  eat.  In  this  chapter  we  shall  include 
in  the  word  "food,"  only  the  portion  of  the  food 

11 


12  PHYSIOLOGY   AND   HYGIENE 

material  that  can  be  taken  into  the  blood,  and  so  can  give 
nourishment  to  the  body  without  injuring  any  of  its 
parts,  and  not  including  that  which  passes  out  as  waste. 

In  order  that  an  engine  may  be  kept  running,  it  is 
necessary,  of  course,  that  coal  or  other  fuel  be  regularly 
supplied,  so  that  the  engine  may  continue  to  have  heat 
under  its  boilers,  and  power  to  run.  But  the  coal 
could  not  keep  the  wheels  revolving  if  an  important 
part  of  the  engine  should  break  down.  The  care  of 
the  engine,  then,  includes  also  the  repairing  or  re- 
placing of  parts  that  break  or  wear  out.  In  much 
the  same  way  our  bodies  need  not  only  heat  and 
energy,  but  also  the  constant  building  and  repair  of 
parts  which  are  used  up  from  day  to  day.  Our  food 
supplies  us  with  material  for  building  and  repair,  as 
well  as  for  heat  and  energy. 

Foods  for  Building  and  Repair.  —  When  you  say, 
"  I  have  grown  two  inches  since  last  year,"  you  mean 
that  your  bones  and  muscles  have  increased  in  size  a 
certain  amount  during  the  last  twelve  months.  Even 
after  we  have  reached  our  full  height,  certain  parts  of 
the  body  still  continue  to  grow.  The  hair  and  finger 
nails  need  frequent  cutting,  and  the  skin  is  all  the 
time  wearing  away.  Although  we  cannot  see  so 
readily  that  the  bones  and  muscles  wear  out  and 
require  constant  repair,  it  is  equally  true.  It  is  neces- 
sary, then,  that  our  bodies  receive  in  food  some  building 
material  which  can  be  used  to  increase  the  size  of 
growing  muscles  and  bones,  and  to  replace  those  parts 
that  are  worn  out. 


FOODS  AND  FOOD  MATERIALS  13 

Foods  for  Fuel.  —  In  addition  to  the  material  used 
for  building  and  repair,  our  bodies  need  food  that  will 
serve  as  fuel,  like  the  coal  on  the  steamship,  to  supply 
heat,  and  power  to  use  the  muscles.  Although  we  may 
feel  so  cold  that  our  bodies  fairly  ache,  as  we  say,  still, 
as  long  as  our  hearts  beat,  that  is,  as  long  as  we  live,  our 
bodies  are  always  warm.  If  you  look  at  a  thermom- 
eter, you  will  see  that  a  certain  point  on  the  scale 
is  marked  "blood  heat."  This  means  that  the  point 
marked  98°  is  about  the  normal  temperature  of  the  blood. 
If  the  blood  is  cooler  than  this,  we  are  ill;  even  a  de- 
gree or  two  of  additional  heat  in  the  body  is  fever.  As 
we  shall  learn  in  a  later  chapter,  our  bodies  are  kept 
at  the  proper  temperature  by  using  up  certain  food 
materials,  much  as  a  stove  or  heater  is  warmed  by  the 
burning  of  coal.  The  flame  which  we  see  when  wood 
or  coal  is  burned  is  caused  by  the  uniting  of  the  fuel 
with  a  gas  in  the  air  which  is  called  oxygen.  In  a 
similar  way,  but  without  flame,  the  heat-giving  foods 
which  we  eat  combine  in  our  bodies  with  the  oxygen 
which  has  been  taken  in  with  the  air  we  breathe. 

KINDS  OF  FOOD 

The  kinds  of  food  which  people  eat  appear  to  be 
numerous.  As  we  study  them  carefully,  however,  we 
find  that  although  our  dinner  table  may  hold  a  number 
of  delicious  things,  the  different  articles  of  food  are 
made  up  of  a  very  few  substances.  Some  of  these 
substances,  of  which  we  shall  learn  more  very  soon, 
furnish  our  bodies  with  both  building  material  and 
fuel,  others  chiefly  with  fuel. 


14  PHYSIOLOGY  AND  HYGIENE 

Let  us  now  consider  these  special  food  substances 
which  are  contained  in  the  things  we  eat. 

Foods  used  for  both  Fuel  and  Repair.  Albumen.  —  If 
we  break  an  egg  carefully,  we  can  separate  the  white 
from  the  yolk.  This  white,  transparent,  jellylike  sub- 
stance is  known  as  albumen,  and  is  a  valuable  food 
substance.  The  white  of  the  egg  is  one  of  the  purest 
forms  of  albumen,  but  though  we  cannot  see  it  so 
readily,  albumen  is  found  in  meat,  milk,  and  other 
articles  of  food.  If  you  heat  the  white  of  the  egg,  it 
becomes  solid,  undergoing  a  change  called  coagulation. 

Myosin.  —  The  lean  part  of  meat  after  the  gristle  has 
been  removed  is  another  important  food  substance,  and 
is  called  myosin.  Uncooked  myosin  is  soft  and  elas- 
tic ;  but  cooking  coagulates  it,  just  as  boiling  hardens 
the  white  of  the  egg. 

Gluten.  —  If  we  wrap  a  little  flour  in  a  piece  of  fine 
muslin  and  allow  water  to  run  through  it,  most  of  the 
flour  will  be  washed  away.  A  sticky,  gummy,  white 
mass  will  be  left.  This  is  gluten. 

Casein. — Milk  contains  a  food  substance  called 
casein.  If  we  pour  a  little  weak  acid,  like  vinegar, 
into  the  milk,  the  latter  curdles.  The  curd,  or  thick 
whitish  substance,  is  casein.  When  pressed  into  cakes 
and  dried  in  a  certain  way,  it  becomes  cheese. 

These  foods,  albumen,  myosin,  gluten,  and  casein,  build 
up  the  body,  help  to  keep  it  in  repair,  and  serye  also  as 
fuel.  They  are  called  proteids,  or  nitrogenous  foods, 
and  without  them  the  body  would  starve.  It  must 
not  be  supposed,  however,  that  eggs,  meat,  flour,  and 


FOODS  AND  FOOD  MATERIALS  15 

milk  are  the  only  proteid  foods,  since  there  is  some 
proteid  in  almost  all  classes  of  foods.  Peas,  beans, 
lentils,  and  similar  vegetables  are  very  rich  in  pro- 
teids, and  are  for  millions  of  people  the  cheapest  and 
most  convenient  of  proteid  foods. 

Foods  used  chiefly  for  Fuel.  —  A  man  might  have  the 
muscles  of  a  Samson,  but  if  he  were  unable  to  lift 
anything  with  his  sinewy  arm,  or  to  run  upon  his  well- 
built  legs,  he  would  be  of  no  more  use  to  the  world 
than  a  statue.  To  enable  us  to  use  our  muscles  we 
need  more  than  the  building  and  repairing  foods ;  we 
must  give  our  bodies  something  that  will  supply 
warmth  and  muscular  power.  The  proteids  or  building 
foods  may  be  used  partly  for  this  purpose,  but  we  have 
in  addition  three  important  food  substances  that  act 
mainly  as  fuels, — starch,  sugar,  and  fats.  They  furnish 
us  with  heat  and  the  power  necessary  for  motion. 
Although  our  diet  cannot  be  confined  to  either  class, 
we  really  need  a  larger  amount  of  the  fuel  foods  than 
of  the  proteids. 

Starch.  —  Starch  is  found  in  certain  of  our  vegetable 
foods,  such  as  flour,  oats,  and  potatoes.  For  use  in 
the  laundry  and  as  stiffening  for  puddingb,  the  starch 
is  separated  from  the  other  substances  found  in  pota- 
toes and  corn ;  we  then  call  it  either  laundry  starch 
or  corn  starch.  We  must  remember,  however,  that 
starch  is  really  present  in  every  potato,  every  kernel 
of  corn,  and  every  grain  of  wheat.  We  can  easily  see 
whether  starch  is  contained  in  a  fruit  or  a  vegetable 
by  touching  it  with  a  drop  of  water  containing  a  little 


16 


PHYSIOLOGY  AND  HYGIENE 


iodine.1  If  there  is  starch  in  the  vegetable,  the  spot 
touched  will  turn  blue.  The  starch  always  appears 
in  the  form  of  very  minute  grains.  Figure  1  shows 
starch  grains  as  they  look  when  seen  through  a  power- 
ful microscope. 

We   can  cook   our   starch  by  putting   a  little   into 
water  and  boiling  it.     The   heat  swells  the  grains  of 
starch  and  the  mass  becomes  a 
thick  paste. 

Sugar.  —  Sugar,  like  starch,  is 
a  fuel  food,  although  in  appear- 
ance and  taste  the  two  differ 
widely.  There  are  several 
kinds,  the  so-called  cane  sugar, 
made  from  sugar  cane,  being  one 
of  the  sweetest.  Beet  sugar, 
manufactured  from  the  sugar 
beet,  is  also  of  excellent  quality.  Grlucose  or  grape 
sugar,  which  is  found  in  fruits  and  in  corn,  is  less 
sweet  than  cane  or  beet  sugar,  but  as  it  is  more  cheaply 
prepared  for  market,  it  is  often  used  for  adulterating 
other  sugars.  Milk  contains  a  kind  of  sugar  known 
as  milk  sugar.  All  sugars  are  of  about  equal  value  as 
foods,  despite  their  different  degrees  of  sweetness. 

We  can  readily  observe  a  difference  between  sugar 
and  starch  by  placing  a  little  sugar  in  water  and  heat- 
ing gently,  and  then  repeating  the  experiment  with 
starch.  The  sugar  quickly  dissolves,  while  the  starch 


FIG.  1.  —  STARCH  GRAINS. 

As  seen  through  a 

microscope. 


1  A  few  drops  of  tincture  of  iodine  in  a  teaspoonful  of  water  is 
sufficient  for  a  number  of  tests. 


FOODS  AND  FOOD  MATERIALS  17 

does  not,  but,  as  we  have  already  seen,  swells  if  the  heat 
is  sufficient. 

Starch  and  sugar,  though  so  different  in  some  re- 
spects, are  closely  related  and  have  much  in  sommon. 
Starch  is  changed  to  sugar  in  fruits  as  they  ripen,  in 
seeds  and  bulbs  as  they  grow,  and  the  same  process 
takes  place  in  our  starchy  foods  as  they  are  digested. 

Fats.  —  Fats  are  among  the  very  best  fuel  foods.  It 
is  because  of  its  excellent  heat-giving  qualities  that 
the  Eskimos  eat  so  much  of  the  blubber  or  fat  of  seals 
and  other  animals  ;  the  fat  enables  them  to  endure  the 
severity  of  their  cold  climate.  Butter,  tallow,  lard,  olive 
oil,  and  cottonseed  oil  are  fats.  Some  of  the  fats  used  as 
foods,  such  as  butter  and  lard,  come  from  animals  ;  and 
others,  such  as  olive  and  cottonseed  oils,  from  the  vege- 
table world.  Several  of  the  fats,  like  lard,  are  solid 
when  they  come  from  the  market,  becoming  liquid 
only  when  subjected  to  heat  ;  others,  like  olive  oil, 
are  always  liquid. 

Animal  fat  is  made  up 
of  little  drops,  each  in- 
closed in  a  sac.  The  sacs 
can  be  seen  only  with 
the  aid  of  a  microscope. 

Figure  2  shows  a  group  FlG*  2-~FAT  CELLS- 

£  £  j.       11  ^       ^  A*  they  appear  in  a  piece  of  meat 

of  fat  cells  as  they  tttw  ^^  a  microScoPe. 


appear  ;  the  figure  shows 
five  fat  drops  in  their  sacs,  in  the  form  in  which  they 
are  found  in  animal  foods,  such  as  a  piece  of  beef- 
steak. We  must  remember,  however,  that  when  we 


18  PHYSIOLOGY  AND  HYGIENE 

look  at  animal  fat  it  is  solid  and  white  because  it  is 
cold.  In  the  living  animal  it  is  liquid,  because  of  the 
heat  of  the  body,  and  it  is  transparent. 

Melted  fats  or  oils,  when  mixed  with  certain  liquids, 
break  up  into  very  small  drops,  making  the  liquids 
look  white.  The  millions  of  minute  fat  drops  in  milk 
aid  in  giving  the  liquid  its  white  color. 

To  test  this,  place  a  few  drops  of  olive  oil  or  castor 
oil  and  some  water  in  a  small  bottle  and  shake  rapidly. 
Then  let  it  stand  for  an  hour  or  so  and  note  the  change. 

Material  for  Bone  Making.  —  As  we  shall  see  later, 
bones  are  made  up  of  two  widely  different  materials. 
Part  of  the  bone,  what  is  called  the  organic  matter,  is 
made  up  from  the  proteids  which  are  so  useful  in  build- 
ing up  other  parts  of  the  body.  The  harder  mineral 
matter  of  the  bone  is  lime,  which  is  contained  in  small 
quantities  in  such  common  foods  as  meat,  bread,  milk, 
and  eggs.  Thus  our  ordinary  food  furnishes  us  with 
all  material  needed  for  bone  building. 

SOURCES  OF  FOODS 

Although  the  substances  about  which  we  have  just 
been  studying  are  the  foods  necessary  to  sustain  life,  we 
seldom  eat  any  one  of  them  singly  or  in  a  pure  form. 
Take  bread,  for  example.  As  usually  made,  it  contains 
flour,  milk,  sugar,  lard,  and  salt.  The  flour  gives  us 
starch  and  gluten,  the  milk  casein  and  sugar,  the  lard 
fat.  And  so  it  is  with  almost  everything  we  eat. 
Usually  several  food  substances  are  to  be  found  in 
each  single  article  of  diet.  See  tables,  pages  33-35. 


FOODS  AND  FOOD  MATERIALS  19 

Foods  come  both  from  animals  and  from  plants.  The 
principal  animal  foods  are  milk,  meats,  and  eggs. 

Milk.  —  Milk  is  one  of  the  cheapest  and  best  of  foods. 
We  may  be  sure,  as  it  is  the  natural  food  for  babies, 
that  it  is  easily  digested  and  contains  all  the  materials 
necessary  for  life,  growth,  and  activity.  The  curd  is 
the  body-building  food,  and  the  cream,  or  fat,  and  the 
milk  sugar  are  the  force-producing  foods.  We  should 
always  remember  that  milk  should  be  used  as  a  food, 
and  not  to  take  the  place  of  water  as  a  drink  to  quench 
thirst. 

Milk  should  usually  be  the  chief  food  for  a  child 
until  his  first  teeth  appear.  When  he  becomes  active 
and  begins  to  walk,  milk  does  not  furnish  enough 
force-producing  material,  and  this  must  be  obtained 
from  starchy  foods,  such  as  bread,  crackers,  and  other 
cereal  foods. 

The  fat  or  cream  may  be  allowed  to  rise  to  the  sur- 
face of  the  milk  and  can  then  be  taken  off  and  churned 
into  butter.  The  skimmed  milk  remaining  still  holds 
most  of  the  sugar  and  just  as  much  of  the  building 
food  as  could  be  found  before  the  cream  was  re- 
moved ;  therefore  it  remains  a  valuable  food.  Skimmed 
milk  contains  a  little  less  fuel  substance  than  does 
new  milk,  but  it  is  equally  serviceable  for  body  build- 
ing. It  is  so  cheap  that  it  is  a  valuable  food  for  those 
who  have  but  little  money  to  spend.  The  curd,  when 
separated  from  the  rest  of  the  milk,  is  pressed  and 
dried  to  make  cheese.  Both  cheese  and  outter  are  very 
useful  foods. 


20  PHYSIOLOGY  AND   HYGIENE 

Danger  in  Milk.  —  Since  milk  is  capable  of  holding 
and  transmitting  the  germs  of  certain  diseases,  it  is 
sometimes  a  source  of  danger.  Typhoid  fever,  diph- 
theria, scarlet  fever,  and  tuberculosis  (consumption) 
are  occasionally  caused  by  impure  milk.  Much  of  the 
illness  suffered  by  babies  and  little  children  in  warm 
weather  may  be  traced  to  milk  which  has  been  made 
impure  by  a  lack  of  cleanliness  about  milkmen,  cows, 
barns,  milk-houses,  or  milk-cans.  It  is  necessary  that 
milk,  and  all  utensils  holding  it,  should  be  kept  per- 
fectly clean.  Some  dealers  send  men  to  inspect  the 
farms  from  which  they  obtain  milk,  to  see  that  every- 
thing about  the  dairy  is  kept  neat. 

To  avoid  these  dangers,  milk  should  be  bought  from 
a  reliable  dealer.  It  should  be  kept  cold  until  used, 
and  all  dishes  in  which  it  is  to  stand  should  be  washed 
with  boiling  water  before  the  milk  is  put  into  them. 
It  is  wise  also,  especially  in  warm  weather,  to  "  scald  " 
the  milk  which  is  to  be  used  by  young  children  or 
invalids.  This  removes  much  of  the  possibility  of 
danger,  and  is  very  little  trouble,  as  the  milk  needs 
only  to  be  brought  to  the  boiling  point  (but  not  boiled) 
and  then  cooled.  Milk  that  has  been  boiled  is  not  so 
wholesome  as  milk  that  has  merely  been  "scalded." 

Meats.  —  Common  meats  consist  of  lean  substance, 
or  flesh,  with  some  fat  and  considerable  water.  The 
flesh  (myosin)  is  one  of  our  most  valuable  body- 
building foods.  So  far  as  the  amount  of  useful  food 
is  concerned,  cheap  meats  are  as  nourishing  as  the 
more  expensive  cuts.  A  pound  of  round  steak  will 


FOODS  AND  FOOD  MATERIALS 


21 


give  us  just  as  much  good  food  as  an  equal  quantity 
of  porternouse  steak.  The  extra  money  for  high-priced 
meat  is  paid  largely  because  these  cuts  are  more  tender 
than  the  cheaper  parts  and  because  the  taste  is  in  some 
respects  better. 

Eggs. — Albumen  and  fats  are  the  principal  foods 
in  eggs.  When  cooked  but  a  little,  whether  boiled 
in  the  shell  or  dropped  into  hot  water,  eggs  are  health- 
ful and  nourishing.  Hard-boiled  eggs  are  less  easily 
digested,  because  the  juices  of  the  stomach  do  not  act 
readily  upon  the  tough,  coagulated  mass.  When  very 
thoroughly  chewed,  however,  they  are  more  readily 
digested. 

Plant  Foods.  —  A  large  part  of  our  food  comes  from 
plants.  The 
most  impor- 
tant of  the 
plant  foods 
are  grains  or 
cereals.  The 
chief  cereals 
eaten  in  this 
country  are 
wheat,  oats, 
rye,  and  corn 
(which  are 
ground  into 

flour,  graham  meal,  oatmeal,  rye  meal,  and  Indian  meal), 
and  rice.  In  the  countries  of  eastern  Asia  rice  is  the 
chief  cereal  used  for  food. 


Starch  Cdls 

Gluten 
Cells 

FIG.  3.— A  SMALL  BIT  OF  A  GRAIN  OF  WHEAT. 
Highly  magnified. 


22 


PHYSIOLOGY  AND  HYGIENE 


All  cereals  contain  a  large  proportion  of  starch,  or 
fuel  food,  and  a  small  amount  of  the  building  materials, 
such  as  gluten.  Wheat,  is  one  of  the  best  cereals, 
since  it  has  more  gluten  (that  is,  more  building  food) 
than  most  of  the  others.  Figure  3  shows  a  small  piece 
of  a  grain  of  wheat  as  it  appears  under  the  micro- 
scope. Some  of  the  cells, 
as  indicated,  are  loaded 
with  starch,  and  others, 
fewer  in  number,  contain 
gluten.  About  one  eighth 
of  our  wheat  flour  is  glu- 
ten. Oats  (Fig.  4)  are 
even  better  food  than 
wheat,  containing,  as  they 
do,  a  still  larger  propor- 
tion of  gluten.  Rice  fur- 
nishes less  building  food 
than  wheat,  but  more  fuel 
food  (starch).  Corn  con- 
tains also  considerable  fat. 
All  of  these  cereals  are 
thus  excellent  foods.  They  give  us  more  fuel  than 
meat  and  eggs,  but  less  of  the  proteids  or  building  foods. 
Wheat  bread  supplies  a  good  proportion  of  the  necessary 
materials  for  fuel  and  repair.  A  person  could  keep  from 
starvation  on  a  diet  of  bread  and  butter  alone,  but  a 
variety  of  foods  is  always  desirable.  Meat  and  cheese  go 
well  with  cereals,  since  they  furnish  the  proteid  and  fat 
elements  lacking  in  the  grains. 


Oat 


FIG.  4.  —  THE  OAT  PLANT. 


FOODS  AND  FOOD  MATERIALS 


23 


Beans  and  Peas.  —  As  beans,  peas,  lentils,  and  peanuts 
contain  large  quantities  of  starch  and  proteids,  they  are 
especially  nourishing  foods.  More  than  one  fifth  of  the 
substance  of  the  bean  is  proteid,  a  larger  proportion 
than  is  contained  even  in  meat.  Although  they  are 
not  so  easily  digested  as  meat,  they  serve  as  an  excel- 
lent substitute,  and  they  are  cheaper. 

Fruits  and  Vegetables.  —  Although  most  fruits  and 
vegetables  contain  little  of  the  real  food  substances, 
they  stimulate  the  appetite  and  thus  give  relish  to  the 
more  substantial  foods.  They  are  composed  largely  of 
water,  with  a  small  amount  of  starch  or  sugar,  flavoring 
matter  which  makes  them  pleasant  to  the  taste,  and  also 
certain  salts  which  aid  digestion. 

Some  of  them,  however,  such  as  potatoes,  beets, 
bananas,  cocoanuts,  and  nuts,  contain  sufficient  starch, 
proteid,  sugar,  or  fat 
to  be  valuable  as 
foods.  Indeed,  vege- 
tables and  acid  fruits 
seem  to  be  needed  by 
the  body,  as  sailors 
or  explorers,  when 
deprived  of  them, 
suffer  from  scurvy 
and  other  diseases. 

Figure  5  represents 

a  bit  of  potato  magnified,  showing  the  grains  of  starch. 
As  the  potato  consists  so  largely  of  starch,  it  is  a  fuel 
food,  and  we  should  eat  with  it  meat,  milk,  cheese,  or 


Starch 

FIG.  5.  —  A  SMALL  BIT  OF  POTATO. 

Highly  magnified.    Showing  cells  filled 

with  grains  of  starch. 


24  PHYSIOLOGY  AND  HYGIENE 

some   other   food  which  will   supply  proteids  for   the 
building  material  which  the  potato  lacks. 

We  may  eat  freely  of  fruits  if  they  are  ripe  and  per- 
fectly sound,  but  unripe  and  overripe  fruits  are  un- 
wholesome and  injurious  to  health. 

OTHER  MATERIALS  NOT  TRUE  FOODS 

There  are  certain  other  substances  which  we  eat  or 
drink  that  are  not  true  foods.  Some  of  them  are  neces- 
sary to  life,  some  of  them  are  of  use,  others  may  be 
harmful.  Let  us  see  what  some  of  these  are. 

Water.  —  The  shipwrecked  sailor  who  is  cast  ashore 
on  a  rocky  island  or  drifts  about  in  an  open  boat  can 
live  for  many  days  without  food,  but  without  water  he 
soon  becomes  almost  crazed  with  thirst,  and  in  a 
very  few  days  he  dies.  Our  blood,  muscles,  and  vital 
organs  all  contain  water.  Without  this  necessary  fluid, 
the  foods  eaten  could  not  be  dissolved  and  thus  made 
ready  for  transformation  into  blood  and  muscle. 

The  various  other  drinks,  such  as  milk,  soda  water, 
tea,  and  coffee,  allay  thirst  only  because  of  the  water 
they  contain,  and  none  of  them  is  equal  to  water  itself  for 
this  purpose.  If  we  quench  our  thirst  with  water  only, 
we  are  not  so  likely  to  drink  too  much  as  we  are  when 
we  attempt  to  satisfy  ourselves  with  liquids  containing 
other  material.  When  we  drink  something  that  has 
an  especially  pleasing  taste,  the  pleasure  of  taste  may 
lead  us  to  drink  more  than  is  wise. 

Cool  water  is  one  of  the  most  refreshing  of  drinks  OD 
a  hot  day,  but  extremely  cold  water,  if  taken  in  large 


FOODS  AND  FOOD  MATERIALS  25 

quantities  when  the  body  is  overheated,  may  produce  a 
shock  which  is  harmful.  Ice  water  or  other  cold  water 
should  be  drunk  very  slowly.  After  violent  exercise  in 
the  hot  sun,  it  is  wise  to  wait  for  a  few  minutes  before 
drinking  cold  water. 

Impurities  in  Water.  —  It  is  not  easy  to  find  abso- 
lutely pure  water.  Some  of  the  impurities  in  drinking 
water  are  harmless  ;  others  are  very  injurious.  Water 
sometimes  contains  certain  minerals  which  it  gets  from 
the  earth.  These  make  the  water  "hard";  but  though 
hard  water  sometimes  produces  slight  bowel  troubles,  it 
is  not  especially  harmful. 

The  most  dangerous  impurities  in  water  are  minute 
living  plants  called  bacteria.  Some  of  these,  as  we  shall 
notice  in  a  later  chapter,  may  produce  disease,  if  they 
are  taken  into  the  body.  One  kind  of  bacteria,  occa- 
sionally found  in  drinking  water,  gives  rise  to  typhoid 
fever.  It  is  impossible  to  judge  either  by  the  appear- 
ance or  by  the  taste,  whether  water  does  or  does  not  con- 
tain injurious  bacteria.  It  may  be  perfectly  clear  and 
of  the  finest  taste,  and  yet  be  unsafe  to  drink. 

Spring  water  is  almost  always  pure,  if  the  spring  is 
deep  and  a  good  distance  from  any  foul  place,  such  as 
an  open  drain  or  a  barnyard.  The  lakes  and  reservoirs 
from  which  cities  obtain  water  are  usually  kept  in  good 
condition  by  the  authorities  ;  if  at  any  time  the  water 
becomes  unfit  to  drink,  people  are  advised  to  boil  it. 
Wells,  particularly  if  they  are  on  a  lower  level  than  the 
houses  or  barns  for  which  they  supply  water,  are  likely 
to  contain  injurious  bacteria.  These  may  either  pass 


26  PHYSIOLOGY  AND  HYGIENE 

down  through  the  soil  or  drain  into  the  wells  from  the 
surface.  River  water  is  usually  unfit  to  drink,  especially 
if  there  are  towns  or  cities  on  the  banks  that  allow 
sewage  to  pour  into  the  stream.  Such  water  can  be 
made  healthful  only  by  boiling.  The  dangerous  bac- 
teria are  destroyed  by  heat.  When  typhoid  fever  pre- 
vails, it  is  always  a  wise  precaution  to  boil  the  drinking 
water. 

Mineral  Substances.  —  Several  mineral  substances, 
called  salts,  are  needed  by  the  body  in  small  amounts. 
Lime  is  required  to  make  bone.  We  eat  common  salt 
with  most  of  our  food.  Although  salt  neither  builds  up 
the  body  nor  supplies  fuel,  it  is  absolutely  necessary  for 
health.  Cattle  will  eat  the  grass  grown  on  salt  marshes, 
in  spite  of  its  coarseness,  because  they  like  the  salty 
taste.  Our  ordinary  food  contains  sufficient  lime  for 
bone  material,  as  well  as  whatever  other  salts,  aside 
from  common  salt,  the  body  requires. 

Flavors.  —  While  we  do  not  partake  of  food  simply 
because  we  enjoy  eating,  still  the  different  articles  of 
diet  give  us  a  certain  pleasure  because  of  their  various 
flavors,  and  indeed  some  flavor  to  our  foods  is  neces- 
sary to  enable  us  properly  to  digest  them.  The  taste 
of  puddings,  cakes,  pies,  and  similar  dishes  is  due 
largely  to  certain  substances  added  to  give  a  desired 
flavor.  The  most  common  of  these  flavorings  are 
lemon,  vanilla,  and  spices.  Tea  and  coffee  are  liked 
partly  because  of  their  pleasant  taste,  partly  because 
of  their  slight  stimulating  effect.  Young  people  are 
better  off  without  them,  and  taken  in  excess  they  are 


FOODS   AND   FOOD  MATERIALS  27 

injurious  to  the  nerves  and  the  digestion  of  every  one, 
Chocolate,  in  addition  to  having  a  fine  flavor,  contains 

real  food. 

ALCOHOL 

Alcohol  is  a  clear,  transparent  liquid,  in  appearance 
resembling  water,  but  very  different  from  water  in  its 
nature  and  effects.  Although  alcohol  is  found  in 
smaller  or  larger  quantities  in  various  materials  used 
for  drinking  purposes,  it  will  neither  quench  thirst  nor 
take  the  place  of  water  in  the  body.  Pure  alcohol  has 
a  strong  odor  and  an  unpleasant  taste. 

Although  alcohol  and  water  appear  so  much  alike, 
we  can  test  the  difference  :  1.  By  smelling  them  — 
water  is  odorless,  while  alcohol  has  a  pungent  odor. 
2.  By  pouring  a  few  drops 
of  alcohol  and  water  into 
saucers  and  applying  a 
lighted  match  —  the  alco- 
hol burns.  3.  By  putting 
salt  into  water  and  also 


into  alcohol-  upon  being  FlG'  6--TBA8T 

Highly  magnified. 
shaken    gently,    the    salt 

dissolves  in  the  water,  while  in  the  alcohol  it  remains 
undissolved.  Similar  results  are  obtained  if  we  sub- 
stitute sugar  for  salt. 

How  Alcohol  is  made.  —  Alcohol  is  made  from  sugar 
by  a  process  called  fermentation.  The  fermentation  is 
brought  about  by  a  minute  plant  called  yeast,  to  be 
seen  only  with  the  aid  of  a  microscope.  The  common 
yeast  which  may  be  purchased  at  the  grocery  store  con- 


28 


PHYSIOLOGY  AND  HYGIENE 


sists  of  many  hundreds  of  thousands  of  these  tiny  plants 
(Fig.  6).  If  a  bit  of  yeast  is  placed  in  a  sirup  made  of 
water  and  sugar  or  molasses,  the  yeast  grows,  feeding 
on  the  sugar  and  very  decidedly  chang- 
ing in  its  nature.  Bubbles  of  gas  rise 
through  the  liquid  in  which  the  yeast 
is  growing  (Fig.  7).  Besides  this  gas 
there  is  produced  at  the  same  time  a 
certain  amount  of  alcohol  which  re- 
mains in  the  liquid.  When  the  sirup 
has  become  entirety  fermented,  the 
sugar  has  disappeared  and  alcohol  has 
taken  its  place. 

It  is  not  always  necessary  to  add 
yeast  in  order  to  start  fermentation. 
Grape  juice  is  changed  into  wine  and 

-Carbonic 

Dioxide-,  apple  juice  into  cider  without  any 
yeast  being  put  into  them.  But  in 
these  cases  a  ferment  gets  into  the 
juice  from  the  air.  These  air  ferments 

solution  are  -n  reaijty  aimost  the  same  thing 
as  the  yeast  from  the  store.  Like 


Sugar 
Solution 


Alcohol 
-left  in 


— Yeast 

T-,      „  yeast  they  are  tiny  plants,  so  small  and 

-b IG.  7.-— ougar 

solution  undergo-  light  that  they  are  blown  about  in  the 
ing  fermentation  air  an(j  are  goon  read  to  act  upon 
by  yeast. 

sugary  liquids  if  they  fall  into  them. 

Fermented  and  Distilled  Liquors.  — Many  kinds  of 
drinks  are  made  by  fermenting  sweet  liquids  obtained 
from  the  juices  of  fruits,  such  as  grapes  and  apples. 
Other  drinks  are  made  from  corn,  barley,  and  various 


FOODS  AND   FOOD  MATERIALS 


29 


grains  by  sprouting  the  grain,  and  thereby  changing 
its  starch  to  sugar,  which  is  then  soaked  out  with 
water.  These  sweet  liquids  are  caused  to  ferment  by 
the  action  of  yeast,  either  added  in  a  form  similar  to 
baker's  yeast  or  carried  into  the  liquids  from  the  sur- 
face of  the  crushed  fruits  or  from  the  air.  The  com- 
mon drinks  made  by  fermenting  sweet  liquids  are  beer, 
ale,  wine,  and  cider.  All  of  these  contain  alcohol  as 
soon  as  they  begin  to  ferment.  It  is  the  alcohol  in 


Beer  Wine  Whisky 

FIG.  8.  —  Showing  the  proportion  of  alcohol  and  water  in 
beer,  wine,  and  whisky. 

these  drinks  that  makes  them  harmful.  The  drinks 
that  contain  alcohol  are  usually  called  liquors.  Those 
obtained  by  fermentation  are  called  fermented  liquors. 
One  danger  of  their  use  is  that  they  cultivate  an  appe- 
tite for  stronger  beverages.  The  amount  of  alcohol 
which  they  contain  ranges  from  one  fiftieth  to  one  fifth 
of  the  total  volume  of  the  liquor.  The  rest  of  the 
material  is  principally  water  (Fig.  8). 

Certain  drinks  called  distilled  liquors  are  made  from 
fermented  mixtures.     By  the  process  known  as  distill- 


30  PHYSIOLOGY  AND  HYGIENE 

ing,  a  part  of  the  water  is  taken  away,  thus  leaving 
a  larger  proportion  of  alcohol  in  the  mixture.  The 
strength  of  the  liquor  depends,  of  course,  upon  the 
amount  of  alcohol  which  remains.  The  proportion  of 
alcohol  in  the  distilled  liquors  used  as  drinks  varies 
from  one  quarter  to  one  half.  The  rest  of  the  material, 
which  is  chiefly  water  with  a  little  flavoring  matter, 
contains  nothing  useful  except  the  water  itself.  The 
distilled  liquors  include  rum,  whisky,  gin,  and  brandy. 
Because  of  their  large  proportion  of  alcohol,  such 
drinks  are  very  harmful.  A  small  amount  of  whisky 
will  intoxicate  much  more  quickly  than  a  large  amount 
of  beer  or  ale. 

There  is  nothing  in  either  fermented  or  distilled 
liquors  that  makes  them  necessary  to  any  person  in 
sound  health.  The  boy  or  girl  who  wishes  to  be  as 
vigorous,  as  useful,  and  as  successful  as  possible  should 
let  them  alone. 

Why  People  drink  Alcohol.  —  Although  when  taken 
in  very  small  quantities  alcohol  acts  as  a  fuel,  its  value 
in  this  respect  is  practically  nothing.1  A  few  cents' 
worth  of  bread  will  furnish  more  heat  and  muscular 
energy  than  a  much  larger  sum  of  money  spent  for  any 
form  of  alcoholic  drink.  Why,  then,  do  people  use 
alcoholic  drinks  ? 

Some  use  them  under  the  mistaken  idea  that  they 
give  muscular  power  and  make  us  stronger.  They  cer- 

1  Although  alcohol  does  thus  act  as  a  fuel,  we  should  not  for  this 
reason  class  it  with  the  fuel  foods,  like  starches  and  sugars,  since  its. 
general  effect  is  to  harm  rather  than  to  benefit  the  body. 


FOODS  AND  FOOD  MATERIALS  31 

tainly  do  not  make  us  stronger ;  their  tendency  is  rather 
to  make  us  weaker,  and  they  do  this  very  decidedly  if 
any  considerable  amount  is  used. 

Sometimes  they  are  used  to  quench  thirst.  But  it  is 
only  the  water  they  contain  that  quenches  thirst,  and 
water  alone  will  do  much  better.  Indeed,  the  alcoholic 
drinks  tend  to  excite  the  thirst  instead  of  quenching  it, 
so  that  people  wish  soon  to  drink  again. 

Some  people  enjoy  the  taste,  although  pure  alcohol 
is  unpleasant  to  the  taste,  and  most  beers  and  wines 
are  disagreeable  at  first  to  the  majority  of  people. 
Then  there  are  those  who  enjoy  the  excitement  which 
the  alcohol  produces,  a  dangerous  enjoyment,  since  it 
may  lead  them  to  do  foolish  or  wrong  things.  Some 
who  have  become  accustomed  to  using  alcoholic  drinks 
find  it  difficult  to  overcome  the  habit.  Here  is  one 
of  the  great  dangers  in  using  alcoholic  liquors.  All 
such  drinks  are  apt  to  create  an  appetite  for  more  and 
more  alcohol.  Many  people  who  seem  to  be  strong 
and  capable  of  resisting  the  appetite,  are  finally  mas- 
tered by  it.  No  one  is  so  safe  from  this  danger  as  he 
who  never  begins  to  use  alcoholic  drinks. 

Intelligent  people  do  not  usually  drink  alcohol  be- 
cause they  consider  it  valuable  as  a  food,  and  if  they 
do,  it  is  a  mistaken  idea.  They  drink  it  because  they 
like  the  taste  or  the  exhilaration  it  produces,  or  be- 
cause they  cannot  overcome  the  appetite  for  it. 


32  PHYSIOLOGY  AND  HYGIENE 

AMOUNT  OF  FOOD  NEEDED 

How  much  food  we  should  eat  is  a  question  not  easy 
to  answer.  The  amount  depends  somewhat  upon  a 
person's  occupation.  If  a  locomotive  is  running  fast, 
it  needs  more  fuel  than  if  it  moves  more  slowly,  and 
when  it  stops,  it  requires  only  sufficient  coal  to  keep 
the  fire  burning.  So  long  as  we  live,  our  bodies  never 
entirely  cease  action,  for  the  heart  always  continues  to 
beat ;  but  at  certain  times  we  are  more  active  than  at 
others,  and  when  we  are  hard  at  work,  more  food  is 
required  than  when  we  rest.  A  poorly  fed  person  can- 
not do  hard  work.  If  a  man,  from  a  false  idea  of  econ- 
omy, subsists  largely  upon  starchy  foods,  like  potatoes 
and  rice,  he  will  be  unable  to  do  as  much  hard  work 
as  his  neighbor  whose  diet  contains  more  of  the  muscle- 
building  materials.  The  man  of  small  income  should 
spend  more  of  his  money  on  beans  or  cheese,  or  per- 
haps on  skimmed  milk,  as  these  will  aid  in  supplying 
strength  for  muscular  work. 

The  using  of  the  body  substance  for  muscular 
strength  can  be  tested  with  the  aid  of  scales.  If  a  boy 
be  weighed  carefully  before  taking  active  exercise  for 
an  hour  or  two,  and  again  after  the  exercise,  the  scales 
will  show  a  difference  in  his  weight.  If  the  weighing 
is  accurate  and  the  boy  has  taken  neither  food  nor 
water  between  the  two  weighings,  the  scales  show  just 
how  much  of  the  body  substance  has  been  used  up 
during  the  muscular  action,  and  consequently  how 
much  food  and  water  are  required  to  replace  the  loss. 


FOODS  AND  FOOD  MATERIALS 


33 


COMPARATIVE  FOOD  VALUES 

The  following  table  shows  the  food  values  which  can 
be  obtained  for  ten  cents  :  — 

COMPARATIVE    COST    OF    DIFFERENT   FOOD    MATERIALS 
AT  AVERAGE  PRICES. 


Amounts  for  ten  cents 

Cost  of 

Total 

Kind  of  Food  Material 

per 
pound 

1  pound 
pro- 
teids i 

weight 
of  food 
material 

Proteid 

Fat 

Starch 

Cents 

Dollars 

Pounds 

Pounds 

Pounds 

Pounds 

Beef,  sirloin 

25 

1.60 

0.40 

0.06 

0.06 

Beef  round              .     . 

16 

.87 

.63 

.11 

08 

Mutton                          .     . 

16 

1.10 

63 

09 

09 

Pork      

18 

1.30 

.56 

.08 

.18 

_ 

Pork-fat,  salt      .... 

12 

6.67 

.83 

.02 

.68 

- 

Butter 

25 

25  00 

40 

32 

Eggs,  24  ^  a  doz.      .     .     . 

16 

1.39 

.63 

.07 

.06 

_ 

Cheese  

16 

.64 

.63 

.16 

.20 

.02 

Milk,  6^  a  qt  

3 

.94 

3.33 

.11 

.13 

.17 

Wheat  flour   .     . 

3 

31 

3.33 

.32 

.03 

2.45 

Corn  meal,  granular    .     . 

*i 

.32 

4.00 

.31 

.07 

2.96 

Wheat  breakfast  food  .    . 

7* 

.73 

1.33 

.13 

.02 

.98 

Oatmeal     

4 

.29 

2.50 

.34 

.16 

1.66 

Rice      

8 

1.18 

1.25 

.08 

.97 

Wheat  bread  

5 

.64 

2.00 

.16 

.02 

1.04 

iieans,  white  dried     .     . 

5 

.29 

2.00 

.35 

.03 

1.16 

Corn,  canned     .... 

10 

4.21 

1.00 

.02 

.01 

.18 

Potatoes,  60  f  a  bush.  .     . 

1 

.67 

10.00 

.15 

.01 

1.40 

1  The  cost  of  one  pound  of  proteids  means  the  cost  of  enough  of  the 
given  material  to  furnish  one  pound  of  proteids,  without  regard  to  the 
amounts  of  other  food  substances  present. 


PHYSIOLOGY  AND   HYGIENE 


Proteids 


This  table  shows  the  comparative  amount  of  the  dif- 
ferent food  materials  which  can  be  purchased  for  ten 
cents.  It  shows  that  beans  give  the  most  proteid  for 
the  money  and  oysters  the  least. 


FOODS  AND   FOOD   MATERIALS 


35 


Proteids       Fats 


Mineral        Carbo- 
Matters       hydrates 


cm 

Water      Refuse 


This  table  shows  the  amount  of  the  different  food 
materials  contained  in  the  different  foods.  From  this 
it  will  be  seen  that  cheese  is  the  most  nutritious  food. 
Beef  is  also  very  nutritious,  but  its  high  price  makes  it 
an  expensive  food,  as  is  shown  by  the  table  on  page  34. 


36  PHYSIOLOGY  AND  HYGIENE 


QUESTIONS 

1.  For  what  purposes  do  we  need  food  ? 

2.  What  are  the  two  classes  of  foods? 

3.  In  what  respect  is  meat  a  valuable  food  ? 

4.  Why  are  beans  especially  useful  as  foods? 

5.  If  we  drink  skimmed  milk,  what  food  will  go  well  with  it  ? 

6.  Of  what  use  to  the  body  are  starch,  sugars,  and  fats  ? 

7.  With  what  does  albumen  furnish  the  body? 

8.  Why  is  milk  made  more  healthful  by  boiling? 

9.  Why  do  people  buy  porterhouse  instead  of  round  steak? 

10.  What  food  substances  do  we  get  from  cereals? 

11.  Why  are  potatoes  so  widely  used  as  foods? 

12.  Which  would  be  the  best  meal :  one  made  up  of  potatoes 
and  rice,  or  one  of  potatoes  and  beans  ? 

13.  Why  are  not  potatoes  alone  a  good  diet?     What  kind  of 
food  should  we  eat  with  them  ? 

14.  What  is  the  chief  use  of  fruits  and  vegetables  ? 

15.  Why  do  we  need  to  drink  water? 

16.  How  can  impure  water  be  made  fit  for  drinking? 

17.  What  does  alcohol  look  like  ?    How  is  it  made  ? 

18.  Why  should    people    abstain   from  the  use   of   alcoholic 
drinks  ? 

19.  Why  do  people  use  alcoholic  drinks? 

20.  What  food  do  we  get  from  cheese  ?    What  does  this  food 
do  for  the  body  ? 

21.  If  you  had  one  dollar  to  spend  for  a  meal  for  four  persons, 
what  would  you  buy  to  make  the  most  useful  meal?     (Consult 
tables  on  pp.  33-35.) 


CHAPTER  II 
DIGESTION 

BEFORE  the  bread  and  butter  which  we  eat  for 
breakfast  becomes  the  blood  and  later  the  muscle  of 
our  body  it  meets  with  a  number  of  changes.  The 
process  by  which  the  food  taken  into  the  body  is 
changed  so  that  it  can  be  absorbed  into  the  blood,  and 
thus  be  used  for  growth,  repair,  and  warmth,  is  called 
digestion.  Certain  organs  of  our  body  have  charge  of 
this  work  and  are  called  the  digestive  organs. 

THE  MOUTH 

The  food  is  received  into  the  mouth,  where  the 
first  step  is  taken  in  preparing  it  to  enter  the  blood. 
The  mouth  is  a  large  cavity  with  the  cheeks  for  its 
sides,  the  tongue  for  a  floor,  and  the  palate  for  a  roof. 
The  front  part  of  the  palate  is  a  hard,  flat  bone.  The 
back  part  is  a  soft  membrane,  with  a  little  finger-like 
piece  called  the  uvula  hanging  from  the  middle  and 
reaching  almost  to  the  tongue.  (See  Fig.  10.) 

The  Teeth.  —  Around  the  sides  and  front  of  the 
mouth  are  two  rows  of  teeth  fastened  securely  in 
sockets  in  the  jawbones.  The  front  teeth  have  sharp 
edges  for  cutting  or  biting  food,  while  those  farther  back 

37 


38  PHYSIOLOGY  AND  HYGIENE 

in  the  mouth  have  broader  surfaces  and  are  used  for 
grinding  or  chewing  the  food  into  a  fine  mass.  Each 
tooth  consists  of  a  crown,  the  part  we  see  as  we  look 
into  the  mouth;  a  neck,  which  is  surrounded  by  the 
gums;  and  a  root,  which  fits  into  the  socket  in  the  jaw- 
bone. Each  tooth  has  a  tiny  blood  vessel  entering 
through  its  root,  and  is  also  supplied  with  a  nerve. 
When  the  nerve  is  exposed  to  the  air  as  a  result  of 
decay,  the  tooth  may  ache.  The  crown  of  the  tooth  is 
covered  with  enamel,  the  hardest  substance  in  the  body. 

Growth  of  the  Teeth. — In  the  course  of  life  we  have  two 
sets  of  teeth.  The  first,  or  temporary  teeth,  begin  to  grow 
when  the  child  is  five  or  six  months  old,  and  they  con- 
tinue to  appear,  one  after  another,  for  about  three  years. 
The  temporary  teeth  are  twenty  in  number.  When 
the  child  is  about  six  years  of  age,  the  second,  or  perma- 
nent teeth,  begin  to  push  their  way  through  the  gums ; 
the  milk  teeth  are  gradually  loosened  as  the  others  push 
their  way  out.  The  first  of  the  permanent  teeth,  called 
the  "  six-year  molars,"  come  so  early  that  they  are  often 
mistaken  for  the  last  of  the  milk  teeth.  The  permanent 
teeth  are  thirty-two  in  number. 

Figure  9  shows  the  permanent  teeth.  Their  arrange- 
ment, as  can  be  readily  seen  from  the  figure,  is  as 
follows,  beginning  at  the  middle  of  the  upper  set:  two 
incisors,  one  canine,  two  bicuspids,  and  three  molars. 
The  other  side  of  the  upper  row  is  similarly  arranged, 
and  the  lower  jaw  holds  sixteen  teeth  to  match  these, 
with  names  corresponding.  Notice  the  sharp  edges  of 
the  front  teeth  and  the  broad  grinding  surfaces  of  the 


DIGESTION 


39 


FIG.  9.  —  THE  UPPER  TEETH. 


double  teeth  farther  back;  also  the  six-year  molars. 
If  you  shut  your  teeth  tightly  together,  you  will  appre- 
ciate how  well  the  upper  and  lower  teeth  match.  The 
edges  of  the  upper 

front     teeth     slip  /D  /~\  (]\.lnusors 

over  those  of  the 
corresponding 
lower  teeth,  so 
that  the  food  may 
be  bitten  off  as  if 
cut  by  scissors. 
The  projections  oi* 
the  upper  back 
teeth  are  opposite 
the  hollows  of  the  corresponding  lower  ones,  so  that 
the  food  may  be  ground  fine  without  difficulty. 

Care  of  the  Teeth. — The  teeth,  when  once  they  are 
fully  grown,  will  never  repair  themselves.  If  A  bone 
of  the  arm  is  broken,  the  two  edges  can  be^set  in  the 
proper  position,  and  the  bone  will  knit,  or  grow  to- 
gether again.  If,  on  the  other  hand,  a  tooth  is  broken 
off  or  worn  out,  it  will  never  repair  itself.  Teeth  are 
liable  to  decay.  The  outside  of  the  tooth,  che  enamel, 
is  hard,  but  the  inside  is  comparatively  soft.  As 
long  as  the  enamel  is  in  perfect  condition,  the  tooth 
will  remain  sound,  but  if  there  is  a  crack  in  the 
enamel,  decay  is  likely  to  start  at  the  crack  and  enter 
the  soft  part  inside.  The  tooth  then  decays  rapidly 
until  it  is  ruined.  Even  a  very  small  hole  in  the 
enamel  may  result  in  a  large  cavity  in  the  softer  sub- 


PHYSIOLOGY   AND  HYGIENE 


stance  within.  We  should  never  pick  the  teeth  with 
anything  hard,  such  as  needles  or  pins,  because  these 
are  liable  to  scratch,  and  so  crack,  the  enamel.  For 
the  same  reason  we  should  not  crack  nuts  or  other 
hard  substances  with  the  teeth.  It  is  also  harmful  to 
the  teeth  to  take  extremely  hot  and  cold  foods  or 
drinks  in  close  succession. 

Particles  of  food  lodged  between  the  teeth  become 
decayed  and  help  to  decay  the  teeth  in  turn.  It  is 
well,  therefore,  to  brush  the  teeth  after  each  meal,  and 
also  at  night,  so  as  to  remove  any  bits  of  food  that 
might  do  injury  if  allowed  to  remain.  To  keep  the 
teeth  healthy  and  sound,  it  is  necessary,  in  addition 

to  brushing 
them,  to  re- 
move, with  a 
soft  toothpick 
or  thread,  all 
bits  of  food 
which  cling  to 
them.  When 
a  tooth  begins 
to  decay,  it 
should  be  at- 
tended to  at 
once  by  a  den- 
tist ;  for  if 

the  small  cavities  are  promptly  filled,  the  tooth  may 
perhaps  be  preserved  for  years,  and  much  pain  and 
expense  be  saved. 


Uvula 
Pi  I /an  of 
Fauces  ». 


FIG.  10, —THE  MOUTH. 
Showing  the  opening  into  the  throat. 


DIGESTION 


41 


Figure  10  shows  the  open  mouth  as  it  appears  when 
we  look  within.  Notice  the  palate  and  the  uvula. 
'By  placing  the  tip  of  the  tongue  on  the  roof  of  the 
mouth  just  inside  the  upper  teeth  and  drawing  the 
tongue  slowly  backward  over  the  roof  of  the  mouth, 
we  can  discover  the  difference  between  the  hard  and 
soft  portions  of  the  palate. 

Salivary  Glands. —  If  some  one  says  the  word  "lemon," 
our  mouths  are  apt 
to  water,  as  we  think 
how  sour  the  juice 
of  the  lemon  is.  The 
fluid  which  moistens 
the  mouth,  and 
whose  flow  is  thus 
increased  by  the  aid 
of  the  imagination, 
comes  from  the 
organs  known  as  the 
salivary  glands.  The 
liquid  produced  is 
called  saliva.  There 
are  three  pairs  of 
salivary  glands. 
Those  who  have  had 
the  mumps  can  locate 

one  of  these  pairs  of  glands  without  difficulty.  These 
are  the  parotid  glands,  which  are  inflamed  and  swollen 
in  that  painful  disease.  They  are  situated  just  below 
and  a  little  in  front  of  the  ears.  There  are  two  sali- 


FIG.  11. — A  DIAGRAM  OF  THE  SIDE  OP 
THE  FACE. 

Showing  the  position  of  the  salivary 
glands  and  their  ducts. 


42  PHYSIOLOGY   AND   HYGIENE 

vary  glands  under  the  lower  jaw  and  two  more  beneath 
the  tongue.  All  these  glands  are  connected  with  the 
mouth  by  little  tubes,  called  ducts,  which  carry  the 
saliva  from  the  glands  into  the  mouth.  The  saliva 
is  poured  out  of  the  tubes  whenever  it  is  needed. 
Although  the  salivary  glands  are  constantly  sending 
out  enough  saliva  to  keep  the  mouth  moist,  the  act  of 
chewing  stimulates  the  action  of  the  glands  so  that  the 
amount  is  largely  increased. 

Figure  11  shows  the  salivary  glands  on  one  side  of 
the  face,  also  the  ducts  that  connect  them  with  the 
mouth. 

FOOD  IN  THE   MOUTH  AND  THROAT 

Need  of  Mastication.  —  After  we  have  taken  a  bite  of 
bread  and  butter,  the  first  step  towards  its  digestion  is 
chewing  or  mastication.  We  chew  our  food  to  break 
it  into  small  pieces  so  that  the  saliva  may  become 
thoroughly  mixed  with  the  food,  and  also  that  the  di- 
gestive juices  may  afterwards  do  their  work  easily. 
The  digestive  juices  in  the  stomach  can  act  only  on  the 
outside  of  each  piece  of  meat,  and  therefore  the  smaller 
the  pieces,  the  shorter  the  time  required  to  digest  them. 

Many  a  person  suffers  from  dyspepsia  as  a  result  of 
the  foolish  habit  of  swallowing  his  food  partly  chewed. 
Rapid  eating  is  injurious,  since  it  forces  the  stomach 
to  do  work  that  belongs  to  the  teeth.  Very  solid  foods, 
like  nuts  or  hard-boiled  eggs,  can  be  digested  properly 
only  after  they  are  thoroughly  chewed.  Some  foods, 
such  as  oatmeal  and  mushes  of  different  kinds,  do  not 


DIGESTION  43 

need  much  mastication,  but  solid  food  should  not  be 
swallowed  until  it  is  ground  into  a  fine  pulp. 

Use  of  Saliva.  —  While  the  food  is  being  chewed  it 
is  moistened  by  the  saliva  that  is  poured  into  the  mouth. 
The  saliva  serves  two  different  purposes. 

1.  Saliva  moistens  the  food  and  the  mouth.  —  If  the 
mouth  becomes  dry,  for  any  reason,  we  are  very  uncom- 
fortable, and  even  talking  is  difficult.    Sometimes,  if  we 
are  frightened,  the  glands  stop  producing  saliva  entirely, 
and  as  a  result  we  find  it  difficult  to  swallow.     How 
impossible  it  is  to  swallow  food  that  is  not  thoroughly 
moist  may  be  comprehended  by  eating  a  cracker. 

2.  Saliva  begins  the  process  of  digestion.  —  The  water 
in  the  saliva  dissolves  some  of  the  foods,  like  sugar, 
but   this   is   not   digestion   proper.      If,  however,   we 
chew  a  bit  of  bread  for  a  few  minutes,  we  find  that 
it  becomes  a  trifle  sweet.     The  saliva  changes  the  starch 
into  sugar.     The  change  begins  as  soon  as  the  food  is 
mixed  with  the   saliva.     It  is   the  beginning  of   real 
digestion,  although  ordinarily  the  starch  does  not  remain 
in  the  mouth  long  enough  for  much  of  it  to  be  thus 
acted  upon.     If  the  food  is  acid  (sour),  as  when  it  is 
mixed  with  vinegar,  no  change  takes  place  in  the  mouth. 

The  amount  of  saliva  in  the  mouth  may  be  increased 
by  chewing  gum.  In  the  case  of  an  athlete  who  wishes 
to  keep  his  mouth  moist  during  exercise,  gum  chewing 
may  be  useful.  Under  ordinary  circumstances,  how- 
ever, not  only  is  the  habit  vulgar  and  impolite  to  the 
people  about  us,  but  the  constantly  stimulated  action 
of  the  salivary  glands  is  probably  injurious. 


44 


PHYSIOLOGY  AND  HYGIENE 


Tonsils.  —  At  the  back  of  the  mouth,  as  may  be  seen 
in  Figure  10,  there  is  a  large  opening  leading  to  the 
throat.  As  soon  as  the  food  is  chewed  and  moistened 
it  is  pushed  back  by  the  tongue  through  this  opening. 
At  each  side  of  the  opening  may  be  seen  a  small 

rounded  body 
called  a  tonsil. 
Sometimes 
when  a  per- 
son has  taken 
cold,  the  ton- 
sils become 
swollen, and  a 
kind  of  sore 
throat  called 


tonsilitis  re- 
sults. It  is 
not  known 
whether  the 
tonsils  have 
a  special  use 
or  not. 

The  Throat. 
—  A  cavity, 
called  the 
throat,  is  situ- 
ated just  back  of  the  mouth.  Into  this  the  food  passes 
after  being  chewed.  The  upper  part  of  the  throat 
opens  into  the  nasal  cavity,  and  from  there,  by  way  of 
the  nostrils,  to  the  exterior.  Thus  both  the  mouth 


FIG.  12. —  A  SECTION  THROUGH  THE  HEAD. 

Showing  the  relation  of  mouth,  throat,  etc. 


DIGESTION  45 

and  the  nostrils  are  connected  directly  with  the  throat. 
Figure  12  shows  this  relation. 

Two  large  tubes  open  downward  from  the  throat. 
One,  the  gullet  or  oesophagus,  extends  to  the  stomach ; 
the  other,  the  windpipe  or  trachea,  connects  with  the 
lungs.  The  windpipe  is  placed  in  front  of  the  oesopha- 
gus, and  it  opens  at  the  top,  so  that  the  air  we 
breathe  may  pass  into  it  readily.  The  opening  is  the 
glottis.  If  a  particle  of  food  drops  into  the  windpipe, 
it  causes  violent  coughing  and  sometimes  choking. 
To  keep  food  from  entering  the  windpipe  as  it  passes 
over  the  entrance  on  the  way  to  the  gullet,  the  wind- 
pipe is  provided  with  an  elastic  lid,  somewhat  like  soft 
India  rubber,  which  rests  upon  the  opening. 

When  we  are  breathing,  this  lid,  which  is  called  the 
epiglottis,  is  lifted  as  in  the  illustration  (Fig.  12);  but 
as  food  passes  from  the  mouth,  the  lid  closes  for  the 
moment  so  as  completely  to  cover  the  opening  into  the 
windpipe  and  allow  the  food  to  slip  safely  over.  As 
soon  as  the  food  has  passed,  the  lid  flies  up  again,  and 
the  windpipe  is  open  once  more,  ready  for  its  regular 
work  of  carrying  air  to  the  lungs. 

If  we  talk  or  laugh  while  our  mouths  are  full  of  food, 
or  while  we  are  drinking,  a  bit  of  the  food  or  water  is 
liable  to  "go  down  the  wrong  way"  ;  that  is,  we  may 
have  the  epiglottis  open  for  a  breath  just  at  the  moment 
the  food  or  water  ought  to  pass  over  to  the  oesophagus. 
Some  of  it  then  drops  into  the  windpipe  instead  of  slip- 
ping over  the  top,  and  violent  coughing  results,  until 
the  foreign  matter  is  coughed  out. 


46  PHYSIOLOGY   AND   HYGIENE 

Figure  12  shows  a  section  of  the  head,  indicating  the 
shape  of  the  throat  and  the  openings  into  the  mouth  and 
nose,  with  the  location  of  the  windpipe  and  oesophagus. 
Notice  the  epiglottis  at  the  top  of  the  windpipe. 

Sore  Throat.  —  Any  soreness  of  the  tonsils,  the  palate, 
or  the  throat  makes  swallowing  painful,  and  we  say  we 
have  a  sore  throat.  Sore  throat,  especially  in  the  case 
of  children,  should  receive  immediate  attention.  If  a 
child  feels  any  soreness  when  swallowing,  his  throat 
should  be  examined,  and  if  there  are  whitish  spots  on 
the  palate  or  the  tonsils,  a  physician  should  be  called 
at  once,  as  the  trouble  may  be  serious. 

Swallowing.  —  After  the  food  reaches  the  throat  it  is 
rapidly  swallowed.  While  food  remains  in  the  mouth 
we  can  control  it,  but  the  moment  it  enters  the  cesopha- 
gus  it  has  passed  beyond  our  control.  If  we  should 
then  discover  that  it  was  poison,  we  should  be  obliged  to 
keep  on  swallowing  just  the  same.  The  food  is  pushed 
through  the  oesophagus  into  the  stomach  by  the  muscles 
of  the  throat  and  oesophagus.  It  does  not  simply  fall, 
but  it  is  actually  forced  'down.  A  person  can  swallow 
water  even  when  he  is  standing  on  his  head,  and  a  horse, 
when  he  drinks,  of  course  swallows  the  water  upward. 

FOOD  IN  THE  STOMACH 

The  Stomach. — A  few  seconds  after  the  food  has 
entered  the  oesophagus  it  passes  into  a  large  cavity  called 
the  stomach  (see  Figs.  13  and  15).  This  is  a  chamber 
similar  to  a  gourd  in  shape,  lying  just  below  the  ribs 
and  a  little  to  the  left  side  of  the  body.  It  is  closed  at 


DIGESTION 


47 


•Oesophagus 


both  ends  by  small  folds  or  valves.  The  valve  between 
the  oesophagus  and  the  stomach  ordinarily  prevents  the 
food  from  going  back  into  the  oesophagus.  Sometimes, 
however,  when  ill- 
ness causes  us  to 
vomit  or  "  throw 
up,"  the  valve  be- 
tween the  stomach  Liver 
and  the  oesophagus 
opens  and  allows 
the  food  to  return 
to  the  mouth.  The 
valve  at  the  lower 
end,  which  con- 
nects with  the  tube 
called  the  intestine, 
prevents  the  food 
from  leaving  the 
stomach  too  soon. 
Figure  13  shows 
the  stomach  with 
its  valves.  The 
stomach  itself  is 
elastic,  and  will 
stretch  so  as  to 
hold  a  large  amount 
of  food,  but  it 

shrinks  again  as  soon  as  the  food  passes  out.  The 
stomach  of  an  ordinary  grown-up  person  can  hold  three 
pints  of  food  very  comfortably. 


Vent 


FIG.  13.  —  THE  DIGESTIVE  ORGANS  OP 
THE  ABDOMEN. 


48 


PHYSIOLOGY  AND   HYGIENE 


The  outer  walls  of  the  stomach  consist  principally  of 
muscular  fibers  which  run  around  it  in  various  directions, 
some  crosswise,  some  lengthwise,  and  some  obliquely. 
As  these  fibers  contract  and  relax,  they  cause  the 
stomach  to  undergo  a  variety  of  motions,  which  mix 
together  the  different  foods  inside  and  keep  them 
moving  around  and  around.  As  long  as  the  food 
remains  in  the  stomach  it  is  thus  kept  in  constant 
motion. 

The  inner  lining  of  the  stomach  contains  hundreds 

Jnner  Surface  of  Stomach 


Gastric 
Glands 


Muscles 


Muscles 


Fio.  14. —  A  SECTION  OP  THE  WALL  OF  THE  STOMACH. 
Highly  magnified. 

of  thousands  of  tiny  glands.  Each  of  these  glands 
is  shaped  somewhat  like  a  little  bottle,  with  its  mouth 
opening  into  the  stomach,  as  shown  in  Figure  14.  The 


DIGESTION  49 

glands  produce  a  liquid  called  gastric  juice,  which  is 
poured  out  of  their  mouths  into  the  stomach. 

Action  of  the  Gastric  Juice.  —  As  soon  as  the  food 
enters  the  stomach,  the  glands  begin  to  pour  gastric 
juice  upon  it.  At  the  same  time  the  stomach,  by  con- 
tracting, begins  to  churn  the  food,  and  mix  it  with 
the  gastric  juice.  In  a  short  time  the  two  are  com- 
pletely mixed,  so  that  the  gastric  juice  can  begin  to 
act  upon  the  food  and  produce  in  it  the  changes  that 
we  call  digestion. 

Action  on  Starch. — When  we  chewed  our  mouthful 
of  bread  until  it  turned  sweet,  we  found  that  the 
saliva  had  changed  some  of  the  starch  in  the  bread 
to  sugar.  This  digestive  action  of  the  saliva  upon  the 
starch  is  stopped  as  soon  as  the  gastric  juice  begins  to 
work  upon  the  food.  This  is  because  the  gastric  juice 
is  an  acid,  and  we  have  already  learned  that  the  presence 
of  anything  sour  prevents  the  action  of  the  saliva  upon 
starch.  The  starch,  then,  is  not  digested  in  the 
stomach,  but  it  will  be  taken  care  of  farther  on. 

Action  on  Meats.  —  A  portion  of  the  work  of  the  gas- 
tric juice  is  to  break  the  food  into  small  parts.  Meat 
is  made  up  of  a  great  number  of  tiny  threads,  called 
muscle  fibers,  which  are  glued  together  by  a  material 
that  holds  them  in  little  bundles.  The  gastric  juice 
dissolves  this  gluey  material,  and  the  fibers  fall  apart. 
Just  as  soon  as  the  juice  gets  them  separated  it  pro- 
ceeds to  act  upon  each  one  separately,  changing  it 
to  a  liquid  form  ready  for  the  blood  to  take  up,  or, 
as  we  say,  digesting  it.  We  have  noticed  (see  Fig.  2) 


50 


PHYSIOLOGY  AND  HYGIENE 


that  the  fat  is  in  little  sacs  held  together  by  a  connect- 
ing mass  of  threads.  Both  the  sacs  and  the  threads 
are  dissolved  by  the  gastric  juice,  so  that  the  fat  floats 
about  freely  in  the  stomach. 

Action  on  Proteids.  — It  is  also  a  portion  of  the  work 

of  the  gastric  juice  to 
get  the  proteids  ready 
for  the  blood  to  use  as 
the  building  material  of 
the  body.  We  found, 
when  we  cooked  the 
albumen  of  the  egg  and 
when  we  caught  the  glu- 
ten of  flour  in  muslin 
cloth,  that  these  proteids 
could  not  be  dissolved  in 
water.  But,  until  these 
substances  are  in  liquid 
form,  they  cannot  be 
taken  up  by  the  blood. 
What  the  gastric  juice 
does  for  the  proteids  is 
to  change  them  in  such  a 
way  as  to  make  it  possible 
for  them  to  dissolve  in 

the  water  that  is  in  the  stomach.  After  the  gastric  juice 
has  done  its  work,  a  part  of  these  glutens,  albumens,  and 
caseins  become  dissolved  and  are  ready  to  enter  the  blood. 
Usually  a  part  of  the  proteid  food  leaves  the  stomach 
undissolved  and  is  changed  to  a  liquid  form  later. 


FIG.  15.  —  SHOWING  THE  LOCATION 
OF  THE  DIGESTIVE  ORGANS. 


DIGESTION  51 

Action  on  Milk. — After  a  hearty  meal  a  baby  often 
throws  up  a  part  of  his  milk  in  a  curdled  condition. 
This  does  not  mean  that  the  stomach  is  "sour,"  but 
simply  that  the  child  has  overfilled  his  stomach.  The 
milk  ought  to  be  curdled  in  the  stomach,  and  if  it 
did  not  curdle,  it  would  mean  that  the  stomach  was 
out  of  order.  The  curdling  has  been  caused  by  the 
gastric  juice.  The  gastric  juice  in  a  baby's  stomach 
curdles  the  milk  more  readily  than  that  in  the  stomach 
of  a  grown  person,  but  under  all  circumstances  curdling 
is  the  first  step  in  the  healthful  digestion  of  the  milk. 
The  curdled  milk  looks  exactly  as  if  it  had  soured. 

We  can  see  just  how  the  curdling  takes  place  by  put- 
ting a  teaspoonful  of  rennet  or  a  rennet  tablet  (to  be 
had  at  the  druggist's)  into  a  cup  of  milk  warmed  to 
about  the  temperature  of  the  body  (98°).  In  the 
course  of  half  an  hour  the  milk  will  be  curdled.  Notice 
that  the  curd,  which  is  casein,  is  a  solid  mass.  In  the 
stomach  this  curd  is  later  dissolved  again. 

Chyme.  —  We  swallow  our  food  in  the  form  of  solid 
meat,  solid  bread,  and  liquid  milk,  and  in  a  short  time, 
from  an  hour  and  a  half  to  three  hours,  it  becomes 
quite  changed.  It  is  now  a  thick  liquid.  The  fats, 
freed  from  their  sacs,  as  we  have  seen,  have  been  melted 
by  the  heat  of  the  body;  the  meat  has  been  divided 
into  threads  and  partly  dissolved;  the  sugars  have  been 
dissolved  in  the  water;  some  of  the  starches  have  been 
turned  to  sugar  and  also  dissolved;  while  the  milk  has 
been  curdled  and  partly  turned  to  liquid  form  again. 
These  materials  have  been  churned  by  the  motions  of 


52  PHYSIOLOGY  AND  HYGIENE 

the  stomach  until  they  are  thoroughly  mixed  together. 
They  now  form  a  gray,  slimy  mass  called  chyme. 

Although  we  pay  no  attention  to  the  matter  and 
think  little  about  it,  our  hearts  continue  their  accus- 
tomed beating,  hour  after  hour  and  day  after  day. 
And  so  it  is  with  the  stomach's  work.  We  do  nothing 
to  supply  the  materials  required  by  the  body  except  to 
eat  when  we  are  hungry,  and  yet  the  wonderful  work 
of  digestion  goes  on,  usually  without  inconvenience 
to  us. 

A  Few  Good  Rules.  —  Though  we  cannot  do  much  to 
help  the  stomach  in  the  churning  and  digesting  process, 
we  may  assist  it  by  our  manner  of  eating  our  food. 
If  we  are  too  thoughtless  of  the  rights  of  the  stomach, 
we  are  certain  to  receive  our  just  punishment  sooner 
or  later  in  the  form  of  indigestion  and  dyspepsia. 

We  can  aid  the  stomach  and  preserve  our  own  health 
by  following  a  few  simple  rules. 

We  should  eat  slowly  and  be  sure  that  the  food  is 
well  chewed  before  it  is  swallowed.  The  habit  of  eat- 
ing often  between  meals  is  very  trying  to  the  stomach, 
since  it  keeps  the  gastric  glands  in  constant  action.  We 
should  never  eat  a  hearty  meal  when  we  are  either  very 
tired  or  very  warm;  it  is  wise  to  rest  first.  No  hard 
work,  either  mental  or  physical,  should  be  entered  upon 
for  at  least  half  an  hour  after  a  hearty  meal.  This  is 
the  stomach's  busiest  time ;  we  should  help  it  as  much 
as  possible  by  keeping  the  rest  of  the  body  quiet. 

We  should  be  careful  as  to  the  quantity  of  water  that 
we  drink  with  our  meals.  Some  water  is  required,  but 


DIGESTION  53 

the  food  should  never  be  "  washed  down  "  with  water. 
Nor  is  it  well  to  drink  much  water  immediately  before 
a  meal.  Ice-water,  if  drunk  at  all,  should  be  sipped 
slowly,  so  that  as  it  passes  down  through  the  throat,  it 
may  be  warmed  more  nearly  to  the  temperature  of  the 
stomach. 

FOOD  IN  THE  INTESTINES 

After  the  food  has  spent  from  one  to  two  hours  turn- 
ing around  and  around  in  the  stomach,  the  fold  forming 
the  valve  or  lid  to  the  intestine  opens  and  allows  a  small 
amount  to  pass  out.  The  contents  of  the  stomach  thus 
from  time  to  time  pass  into  the  intestines,  until,  at  the 
end  of  three  or  four  hours,  the  outlet  relaxes  and  allows 
the  remaining  food  to  leave  the  stomach,  even  though 
some  of  the  particles  may  still  be  quite  solid.  The 
stomach  is  now  empty,  and,  after  a  rest,  is  ready  for  the 
next  meal. 

The  Intestines. — The  food  which  has  passed  through 
the  opening  at  the  lower  and  smaller  end  of  the  stomach 
enters  the  intestines,  more  commonly  called  the  bowels. 
The  intestines  consist  of  a  long  tube,  very  much  coiled, 
filling  the  larger  part  of  the  abdomen  below  the  stom- 
ach, as  is  shown  by  Figures  13  and  15.  The  part  which 
is  connected  with  the  stomach,  or  the  small  intestine,  is 
from  one  to  two  inches  in  diameter,  and  about  twenty 
feet  long.  The  large  intestine  is  about  two  and  one 
half  inches  in  diameter  and  five  feet  long. 

The  Liver.  —  We  all  have  seen  the  liver  of  the  ox  or 
calf  either  exposed  for  sale  at  the  market  or  on  the 
breakfast  table  cooked  with  bacon.  The  human  liver 


54  PHYSIOLOGY  AND  HYGIENE 

resembles  the  ox  liver  very  closely.  It  is  of  a  dark 
red  color,  and  lies  a  little  above  and  at  the  right  of 
the  stomach.  It  is  one  of  the  largest  organs  in  the 
body,  weighing  several  pounds,  and  it  is  one  of  the 
most  important.  It  produces  a  liquid  called  bile.  The 
bile  passes  through  a  tube  and  empties  into  the  intes- 
tines near  the  stomach.  When  digestion  is  not  going 
on,  the  bile  collects  in  a  little  sac  at  the  lower  side 
of  the  liver,  known  as  the  gall  bladder.  Figure  13 
shows  the  liver,  the  gall  bladder,  and  its  tube  or  duct. 

The  Pancreas. — The  pancreas  is  a  long,  somewhat 
thin  gland,  placed  just  below  the  stomach.  This  also 
produces  a  liquid  secretion  which  passes  through  a  tube 
and  empties  into  the  intestines.  This  liquid,  which  is 
called  the  pancreatic  fluid,  empties  into  the  intestines 
with  the  bile.  Thus  the  food  from  the  stomach  is 
mixed  with  the  bile  from  the  liver  and  the  fluid  from 
the  pancreas  almost  as  soon  as  it  enters  the  intes- 
tines. Notice  the  pancreas,  with  its  duct,  as  shown  in 
Figure  13. 

Use  of  the  Liver.  —  Probably  most  of  us  know  from 
experience  how  a  person  looks  and  feels  when  he  is 
"bilious."  The  skin  becomes  a  dull  yellow,  the  eyes 
lose  their  sparkle,  and  the  person  seems  to  lose  all 
his  ambition  without  being  sufficiently  ill  to  be  con- 
fined to  his  bed.  The  trouble  is  that  the  bile  has 
ceased  to  pass  freely  from  the  liver.  The  bile  aids  the 
pancreatic  fluid  in  its  work  of  digestion,  especially  on 
fats,  tends  to  prevent  decomposition  in  the  contents  of 
the  intestines,  and  aids  in  the  regularity  of  the  action 


DIGESTION  55 

of  the  bowels.  But  the  bile  is,  however,  chiefly  a  waste 
product,  and  it  pours  into  the  intestines  partly  as  a  way 
of  disposing  of  itself.  The  liver  has  several  functions  to 
perform ;  one  of  the  most  important  is  to  help  to  remove 
this  waste  material.  When,  for  any  reason,  the  bile 
cannot  thus  escape  into  the  intestines,  it  passes  back 
into  the  blood  in  the  liver,  and  is  then  carried  to  all 
parts  of  the  body,  producing  illness  and  turning  the 
skin  to  a  peculiar  yellow.  We  then  say  we  are  bilious. 

Changes  in  the  Intestines.  —  As  soon  as  the  food  enters 
the  intestines  it  is  mixed  with  the  secretions  from  the 
liver  and  pancreas.  Further  changes  are  at  once  pro- 
duced in  the  food,  principally  by  the  pancreatic  fluid. 
The  pancreatic  juice  acts  upon  all  kinds  of  food  in  such 
a  way  as  to  make  liquid  those  not  already  dissolved. 

Starch.  —  We  have  learned  that  most  of  the  starch 
escapes  from  the  mouth  without  being  turned  into 
sugar  by  the  saliva  and  passes  into  the  stomach  and 
out  again  to  the  intestines,  still  in  the  form  of  starch. 
But  the  pancreatic  juice  has  just  the  same  effect  on 
starch  as  has  saliva  —  it  turns  the  starch  to  sugar. 
The  pancreatic  juice  takes  up.  and  completes  this  work 
of  changing  starch  into  sugar.  The  sugar  is  then  dis- 
solved like  all  of  the  other  food. 

Proteids.  —  The  pancreatic  juice  has  the  same  effect 
upon  the  proteids  as  the  gastric  juice.  It  changes  into  a 
soluble  form  any  proteids  that  may  have  passed  into  the 
intestines  in  solid  state,  whether  they  be  the  lean  part 
of  meat,  the  gluten  of  the  wheat,  or  the  casein  of  milk. 
The  food  in  the  intestines  becomes  more  and  more  liquid. 


56  PHYSIOLOGY  AND  HYGIENE 

Fats.  —  The  last  we  knew  of  the  fats  they  formed  an 
oily  mixture  in  the  stomach,  where  the  gastric  juices 
could  not  act  upon  them.  When  they  pass  into  the 
intestines  the  pancreatic  juice  begins  to  digest  them. 
We  have  already  seen  that  when  we  shake  olive  oil 
with  water,  the  water  separates  the  oil  into  minute 
drops  that  float,  making  the  liquid  look  milky.  In  a 
somewhat  .similar  way  the  pancreatic  juice  acts  upon 
the  fats  as  they  pass  along  the  intestines.  It  breaks 
the  fat  into  millions  of  tiny  drops  which  are  mixed  with 
the  contents  of  the  intestines,  giving  the  whole  mass  a 
milky  white  appearance.  The  breaking  up  of  the  fat 
into  drops  is  the  digestion  of  fat.  The  fat  is  not  actu- 
ally dissolved  like  the  sugar,  but  when  it  is  broken  up 
in  this  way  the  particles  of  fat  are  small  enough  to 
pass  into  the  blood. 

Chyle.  —  The  food  was  swallowed  as  solid  bread, 
meat,  and  potatoes,  but  now,  after  from  two  to  four 
hours  or  more,  it  has  become  in  the  intestines  a  milk- 
white  liquid,  somewhat  thicker  than  milk,  but  not  so 
thick  as  molasses.  It  is  called  chyle,  and  it  contains 
most  of  the  foods,  dissolved  into  liquid  form.  The 
food  is  now  ready  to  be  absorbed  into  the  blood  vessels. 

THE  DIGESTIBILITY  OF  FOODS 

If  our  food  were  not  digested,  it  would  be  of  no  more 
use  to  us  than  stones,  for  it  could  not  be  taken  into  the 
blood.  People  who  have  weak  digestive  organs  suffer 
from  lack  of  food,  no  matter  how  much  they  eat.  For 
this  reason  the  value  of  the  food  we  eat  depends  as 


DIGESTION  5T 

much  upon  whether  it  is  easily  digested  as  upon  the 
food  substances  that  it  contains. 

Cheese,  for  example,  contains  a  very  large  amount 
of  valuable  food,  but  it  is  so  hard  to  digest  that  it  is 
less  useful  than  meat,  which,  although  it  contains  less 
food  than  cheese,  digests  more  easily.  Beans  are  in 
some  respects  a  more  nourishing  food  than  meat,  but  as 
they  do  not  digest  so  easily,  much  of  their  value  may 
be  lost,  passing  away  in  the  waste. 

In  choosing  what  we  shall  eat  we  should  be  careful 
not  to  load  the  stomach  with  food  hard  to  digest. 
Although  it  is  perfectly  safe,  if  we  are  strong  and  well, 
to  eat  some  foods  that  do  not  digest  easily,  we  should 
not  do  so  frequently.  The  following  table  will  give  us 
a  little  idea  of  some  of  the  more  easily  digested  foods 
and  some  of  those  less  easily  digested :  — 


FOODS  EASY  TO  DIGEST 


FOODS  DIFFICULT  TO  DIGEST 


Milk 

Bread 

Rice 

Raw  oysters 

Soft-boiled  eggs 

Boiled  beef 

Mutton 

Boiled  chicken 

Broiled  meats 


Fried  foods 

Beans  and  peas 

Hard-boiled  eggs 

Pork 

Veal 

Cheese 


Boiled  or  broiled  foods  are,  in  general,  more  quickly 
digested  than  those  that  are  roasted,  because  boiling 


58 


PHYSIOLOGY  AND  HYGIENE 


softens  the  solid  foods  so  that  the  digestive  fluids  can 
act  upon  them.  Fried  foods  are  more  difficult  to  digest 
than  the  same  foods  cooked  in  any  other  way,  since 
the  frying  is  apt  to  soak  the  food  with  fat,  which  makes 
it  difficult  for  the  digestive  juices  to  act. 

HOW  THE  FOOD  GETS  INTO  THE  BLOOD 

All  this  process  has  not  yet  put  the  food  where  it 
can  be  used  to  build  up,  repair,  warm,  and  provide 
muscular  power  for  the  body.  We  are  now  ready  for 
the  final  chapter  of  our  story  —  how  the  digested  food 
gets  into  the  blood. 

We  have  learned  that  by  the  time  the  food  has  been 

in  the  intestines 
from  two  to  four 
hours  it  has  all 
become  digested 
Ve,sse/»  and  turned  into 
chyle.  The  long  in- 
testinal tube  which 
holds  the  chyle,  is 
not  loose  in  the 
body,  bat  is  held 
in  position  by  a  thin 
sheet.  Such  a  sheet 
is  called  a  mem- 
brane, and  this  par- 
ticular one  is  the  mesentery.  It  is  folded  many  times 
and  is  wrapped  around  the  intestines  as  shown  in  Figure 
16.  There  are  many  blood  vessels  in  the  mesentery, 


bloodvessel* 
Lacttab  or 


FIG.  16.  —  A  BIT  OF  THE  INTESTINE. 

Showing  how  it  is  held  in  position  by  the 

mesentery. 


DIGESTION 


59 


some  of  them  carrying  blood  to  the  intestines,  and 
others  carrying  the  same  blood  away  again.  These 
blood  vessels  take  away  a  large  part  of  the  digested  food. 
A  bit  of  the  intestinal  wall  is  shown  in  Figure  17. 
The  wall  is  rather  thick  and  has  two  layers  of  muscles., 

A1" 


Glands 


Vj» 


FIG.  17. — A  BIT  OF  THE  INTESTINE. 

Showing  the  muscles,  glands,  and  the  numerous  villi  on  its 

under  surface.    Moderately  magnified. 

The  inside  surface  is  covered  with  tiny  projections, 
like  little  fingers,  extending  inward.  They  are  called 
villi.  Figure  17  shows  some  of  the  villi  enlarged,  so 
that  we  may  see  what  they  are  like.  Villi  are  really 
so  very  tiny  that  they  can  only  just  be  seen  with  the 
naked  eye.  There  are  millions  of  them,  so  many  that 
they  line  the  whole  inside  of  the  intestines,  giving  it  a 
soft,  velvety  surface. 

Duties  of  the  Villi.  —  The  villi  are  very  interesting  to 
study,  for  they  take  the  digested  food  out  of  the  intes- 
tines and  give  it  to  the  blood.-  Unlike  the  glands  of 


60 


PHYSIOLOGY  AND   HYGIENE 


)ithelium 


the  stomach,  of  which  we  have  learned,  these  villi  have 
no  opening  into  the  intestines.  Their  walls,  however, 
are  so  thin  and  so  delicate  that  the  dissolved  food  can 
pass  through  them  readily.  A  single  one  of  these  little 

bodies,  much  magnified,  is 
shown  in  Figure  18.  It  is 
covered  on  the  outside  with 
tiny  cells,  which  form  the 
epithelium.  Inside  there 
are  a  great  many  minute 
blood  vessels.  One  blood 
vessel,  the  artery,  brings 
blood  into  the  villus,  and 
another,  the  vein,  takes  it 
away.  The  artery  brings 
the  blood  from  the  heart; 
the  vein  carries  it  away  to 
the  liver. 

Just  how  the  villi  take 
the  food  and  send  it  where 
it  belongs  is  a  particularly 
interesting  chapter  in  our 
story  of  digestion.  The 
white  chyle  moving  along 
the  intestines  bathes  the 
villi  as  it  passes.  Each  little 
villus  is  constantly  at  work 

taking  the  digested  food  from  the  chyle  as  it  comes 
along,  leaving  the  undigested  and  waste  matters.  The 
dissolved  sugars  and  albumens  pass  through  the  thin 


of  Lad 

Fm,  18.  —  A  SINGLE  VILLUS. 
Highly  magnified. 


DIGESTION 


61 


Water 


membrane  into  the  inside  of  the  villus.  Even  the  par- 
ticles of  fat  are  seized  and  passed  into  the  inside.  Thus 
as  the  food  passes  on  through  the  intestines,  more  and 
more  of  it  is  taken  up  by  villi,  until  most  of  the  useful 
part  has  been  removed*  The  way  in  which  this  food  is 
taken  into  the  intestines  is  illustrated  in  Figure  19.  A 
bladder  is  tied  tightly 
upon  a  tube  and  filled 
with  water,  and  the 
whole  is  then  lowered 
into  a  dish  containing 
some  sugar  dissolved  in 
water.  It  will  be  found 
after  a  little  time  that 
the  water  inside  of  the 
bladder  has  become 
sweet.  The  sugar  has 
passed  from  the  dish 
into  the  bladder.  In 
much  the  same  way  the 
sugars  and  other  foods 
pass  from  the  intestines 
into  the  villi. 

After  the  food  gets  into  the  villi  it  does  not  all  go  in 
the  same  direction.  The  sugars,  proteids,  water,  and 
salt  are  taken  out  of  the  villi  by  their  tiny  blood  vessels 
and  are  carried  away  in  the  blood  to  the  liver.  Of 
course  the  starch  has  already  been  turned  to  sugar  by 
the  digestive  processes,  so  that  all  the  foods  go  to  the 
liver,  except  the  fat. 


FIG.  19.  —  A  simple  device  for  show- 
ing how  foods  may  pass  through 
membranes,  as  they  do  when  they 
enter  the  villus. 


62  PHYSIOLOGY  AND  HYGIENE 

The  fat  takes  a  different  direction.  It  does  not  enter 
the  blood  vessels  of  the  villi  at  all.  The  middle  of  the 
villus,  as  shown  in  Figure  18,  is  a  clear  space  called  a 
lymph  vessel  or  lacteal.  This  opening  or  tube  is  made 
to  receive  the  fat,  and  the  little  drops  of  fat  pass 
directly  into  it.  The  vessels  are  called  lacteals,  which 
means  milk  holders,  because  the  liquid  fat  with  which 
they  are  filled  is  white  like  milk.  After  taking  the  fat 
from  the  intestines  the  lymph  vessels  empty  it  into 
larger,  similar  vessels  and  these  empty  into  still  larger 
ones  which  pass  through  the  sheet  of  membrane  sur- 
rounding the  intestines.  The  large  lacteals  pass  up 
through  the  chest,  back  of  the  heart,  and  empty  the  fat 
into  one  of  the  large  blood  vessels  in  the  neck,  so  that  all 
of  the  absorbed  food  material  finally  reaches  the  blood. 

There  are  thus  in  the  membrane  shown  in  Figure  16 
three  sets  of  tubes :  1.  Blood  vessels  bringing  blood  to 
the  intestines.  2.  Other  blood  vessels  carrying  the  blood 
which  has  taken  up  food,  from  the  intestines  to  the  liver. 
3.  Lacteals  carrying  fat  to  the  blood  vessels  in  the  neck. 

UNDIGESTED  PORTIONS  OF  THE  FOOD 

We  have  learned  that  the  food  passes  from  the 
stomach  through  the  intestines.  The  material  is  kept 
moving  by  a  contraction  of  the  wall  of  the  intestines. 
This  contraction  causes  a  gentle  writhing  motion  of 
the  intestines,  which  forces  the  food  slowly  along. 
The  movement  is  somewhat  similar  to  the  wriggling 
of  an  earthworm  as  it  tries  to  make  its  way  along 
the  surface  of  the  ground.  As  the  food  mass  passes  on, 


DIGESTION  63 

the  villi  take  up  more  and  more  of  what  can  serve  the 
body  as  real  food,  together  with  much  of  the  water. 
-  Finally,  very  little  is  left  in  the  intestines  except  undi- 
gested refuse,  together  with  excretions,  like  bile,  which 
are  of  no  further  use.  These  are  waste  materials.  As 
more  and  more  of  the  water  and  dissolved  food  are 
absorbed,  the  waste  materials  become  quite  solid,  until 
they  pass  out  of  the  body.  The  bowels  should  get  rid 
of  the  waste  material  every  day.  Regular  habits  in 
this,  respect  are  necessary  for  avoidance  of  discomfort 
and  of  sickness. 

Now  the  story  of  food  digestion  is  nearly  completed. 
Let  us  recall  briefly  the  history  of  our  piece  of  bread 
and  butter.  It  was  carried  to  the  mouth,  and  was 
bitten  off  and  chewed  by  the  teeth.  With  the  aid  of 
the  saliva  it  was  moistened  and  then  swallowed.  After 
a  safe  passage  over  the  windpipe,  the  oesophagus  carried 
it  to  the  stomach.  There  it  was  thoroughly  churned 
and  mixed  with  gastric  juice.  Little  by  little  it  passed 
from  the  stomach  into  the  intestines,  was  mingled  with 
the  bile  and  pancreatic  juice,  and  then  the  digested  part 
was  taken  up  by  the  villi,  leaving  the  waste  materials 
to  be  discarded.  As  we  shall  see  later,  the  food  material 
finally  reaches  through  the  blood  all  the  parts  of  the 
body  which  need  it  for  growth  or  work. 


64  PHYSIOLOGY  AND   HYGIENE 


QUESTIONS 

1.  What  is  meant  by  digestion  ? 

2.  Why  is  it  necessary  to  digest  food  ? 

3.  What  are  the  parts  of  the  mouth  ? 

4.  Of  what  parts  does  a  tooth  consist  ? 

5.  How  many  permanent  teeth  are  there  ?    What  are  their 
names? 

6.  What  causes  a  tooth  to  decay? 

7.  What  and  where  are  the  salivary  glands? 

8.  What  are  the  uses  of  saliva? 

9.  What  prevents  food  from  passing  into  the  windpipe  instead 
of  the  O3sophagus  ? 

10.  How  does  the  stomach  digest  the  food? 

11.  What  is  the  action  of  the  gastric  juices  on  meats  ?    On 
proteids  ?    On  milk  ? 

12.  What  is  chyme? 

13.  What  are  the  liver  and  the  pancreas? 

14.  Of  what  use  is  the  liver  ? 

15.  What  changes  are  made  in  starch,  proteids,  and  fats  in  the 
intestines? 

16.  What  is  chyle? 

17.  How  does  the  food  get  into  the  blood? 

18.  If  you  chew  finely  a  piece  of  meat,  does  saliva  start  its 
digestion  ?    How  would  it  be  with  bread  ? 

19.  Notice  your  method  of  swallowing,  and  see  if  you  use  your 
tongue. 

20.  What  part  of  a  lunch  of  bread  and  butter  is  digested  in  the 
mouth  ?    What  in  the  stomach  ?     What  in  the  intestines  ? 

21.  Since  cheese  is  made  of  milk,  why  is  it  not  a  good  food  for 
babies  ? 


CHAPTER  III 
FOOD   HABITS   AND   COOKING 

Unwise  habits  with  regard  to  eating  and  drinking 
are  probably  the  cause  of  more  sickness  than  anything 
else.  Indigestion,  which  is  very  common,  may  fre- 
quently be  remedied  more  easily  by  changing  the  habits 
of  eating  and  drinking  than  by  taking  medicine. 

PROPER  HABITS  OF  EATING 

Suppose  a  company  of  boys  from  different  parts  of 
the  world  should  come  together  for  a  picnic.  Their 
lunch  baskets  would  contain  a  good  variety  of  what  the 
owners  would  consider  delicacies.  The  American  boy 
would  probably  have  sandwiches  and  cake;  the  German, 
rye  bread  and  sausages;  the  Chinese,  some  form  of  rice; 
the  young  Eskimo,  a  fish  or  a  piece  of  seal.  Each  boy 
would  be  well  nourished  and  satisfied,  if  only  he  had 
enough  of  his  own  kind  of  food.  In  other  words,  just 
what  we  eat  is  largely  a  matter  of  custom  and  climate. 

We  are  mistaken  if  we  think  we  must  have  certain 
kinds  of  food,  for  we  can  adapt  ourselves  to  almost 
anything,  provided  it  is  nutritious  and  digestible, 
We  have  a  very  large  variety  of  foods  from  which 
to  choose,  but  it  is  wise  to  adapt  the  appetite  to 

05 


66  PHYSIOLOGY  AND  HYGIENE 

what  is  conveniently  obtained.  We  should  particularly 
guard  against  allowing  ourselves  to  be  controlled  wholly 
by  taste,  and  we  should  not  refuse  to  eat  what  is  whole- 
some just  because  we  fancy  it  is  not  quite  to  our  liking. 
Substances  with  very  strong  taste,  like  mustard,  for  in- 
stance, we  may  properly  refuse  whenever  they  are  dis- 
tasteful, but  there  is  no  sensible  reason  for  objecting  to 
a  dish  of  oatmeal;  we  can  eat  it,  and  learn  to  like  it,  if 
we  will. 

Cost.  —  People  with  small  incomes  are  likely  to  live 
principally  upon  starchy  foods,  such  as  bread,  rice,  or 
potatoes,  because  these  are  comparatively  cheap.  But 
we  cannot  live  upon  starch  and  sugar  alone.  We  must 
all  of  us  have  some  proteids.  If  we  will  remember  that 
we  can  get  our  proteids  cheapest  in  beans  and  cheese, 
we  shall  be  able  to  make  better  use  of  our  money  than 
by  spending  it  all  for  starchy  foods.  A  simple  meal  of 
bread,  butter,  milk,  cheese  or  meat,  and  some  vege- 
tables, with  perhaps  a  dessert  of  fruit  or  a  simple  pud- 
ding, is  far  better  than  a  heavy  dinner,  with  numerous 
courses.  Some  people  make  the  mistake  of  having 
too  many  kinds  of  food  at  one  meal,  many  of  them 
highly  seasoned.  The  pleasurable  taste  encourages 
us  to  eat  more  than  the  body  requires,  and  the  result 
is  frequently  a  loss  of  healthy  appetite.  The  man  who 
spends  a  great  deal  of  money  for  his  food  usually  gets 
less  pleasure  from  it  than  the  one  who  lives  upon  plain 
foods  varied  by  an  occasional  luxury. 

Times  for  Eating.  —  Most  people  in  this  country  eat 
three  meals  a  day.  In  some  countries  four  or  five 


FOOD  HABITS  AND  COOKING  67 

meals  are  the  rule,  in  others  only  two  or  even  one. 
Whatever  our  habit  in  this  regard,  we  should  eat  at 
certain  specified  times,  so  that  the  stomach  may  be 
called  upon  to  work  regularly,  and  may  also  have  a 
chance  to  rest. 

We  frequently  hear  that  candy  is  injurious,  although 
we  have  learned  that  sugar  is  a  useful  food.  The  trouble 
is  not  with  the  candy,  but  with  our  abuse  of  it.  If  we 
have  sweets  in  our  possession,  we  are  apt  to  be  munch- 
ing them  all  day  long,  keeping  the  stomach  constantly 
at  work.  Moreover,  the  pleasant  taste  of  the  candy  is 
likely  to  make  us  eat  too  much,  so  that  we  suffer  from 
overeating.  Some  people,  especially  children,  like  to  be 
eating  all  the  time.  This  is  very  unjust  to  the  stomach. 
Continuous  good  health  is  impossible  unless  the  stomach 
and  other  digestive  organs  are  given  regular  times  to 
rest  as  well  as  to  work. 

Although  breakfast  is  an  important  meal,  it  need  not 
be  a  heavy  one.  Nor,  on  the  other  hand,  ought  we  to 
make  too  light  a  meal  of  it.  This  error  often  leads  to 
headache,  faintness,  and  weakness  before  the  noon  meal. 
Fruit,  oatmeal  or  some  other  cereal,  and  eggs,  with 
bread,  form  an  excellent  breakfast.  There  is  no  better 
drink  to  go  with  it  than  water.  Milk,  chocolate  or 
cocoa  may  also  be  taken,  but  we  should  remember  that 
they  are  foods  as  well  as  drinks.  The  heartiest  meal 
should  be  in  the  middle  or  at  the  close  of  the  day,  and 
should  be  followed  by  rest  of  at  least  an  hour.  A  little 
food  before  going  to  sleep  at  night  helps  some  to  rest 
easily.  A  glass  of  hot  milk  taken  just  before  a  person 


68  PHYSIOLOGY  AND   HYGIENE 

retires  is  frequently  an  excellent  remedy  for  habitual 
wakefulness. 

The  Appetite  as  a  Guide.  —  When  we  are  in  need  of 
food  we  feel  hungry,  and  when  we  need  water  we  are 
thirsty.  Hunger  and  thirst  are,  then,  the  guides  given 
us  by  nature  to  indicate  the  want  of  food  and  water. 
If  we  treat  them  wisely,  they  guide  us  well,  so  long  as 
we  are  in  good  health.  But  these  appetites  may  be 
abused  so  that  we  cannot  follow  them  safely.  Some 
people,  especially  children,  continue  to  eat  anything 
that  they  happen  to  like  particularly,  even  after  their 
desire  for  food  is  gone,  and  they  keep  on  drinking 
pleasant  tasting  liquids  after  the  thirst  is  quenched. 
This  is  almost  sure  to  do  injury. 

We  should  eat  to  satisfy  the  desire  for  food.  One 
who  continues  eating  after  the  body  has  taken  suffi- 
cient nourishment  is  both  foolish  and  intemperate. 
Overindulgence  in  eating  is  probably  one  of  the  most 
common  causes  of  ill  health.  It  is  always  wise  to  stop 
eating  as  soon  as  the  food  ceases  to  be  relished  as  much 
as  it  was  when  the  meal  began,  instead  of  continuing 
to  eat  until  there  is  a  feeling  of  fullness  in  the  stom- 
ach. If  we  make  this  a  habit,  we  are  not  likely  to 
suffer  either  from  eating  too  little  or  from  eating  too 
much. 

Pleasure  in  Eating.  —  The  old  proverb,  "  Laugh  and 
grow  fat,"  is  a  saying  with  sound  sense  behind  it. 
Good  temper  and  merriment  certainly  aid  digestion. 
Mealtimes  should  be  among  the  pleasantest  occasions 
of  the  day.  There  is  no  reason  why  we  should  not 


FOOD  HABITS  AND  COOKING  69 

enjoy  partaking  of  the  food,  as  well  as  take  pleasure 
in  the  companionship  of  those  who  share  our  table. 
This  enjoyment  is  lost  in  many  homes,  not  only  through 
making  mealtimes  the  occasion  for  disputes,  but  by  the 
unfortunate  habit  of  "  bolting  "  the  food,  which  renders 
conversation  an  impossibility,  and  takes  away  all  pleas- 
ure in  the  food  itself. 

Overeating,  eating  rich  foods  in  great  variety,  and 
eating  too  frequently  and  rapidly,  are  the  causes  of 
most  of  the  indigestion  so  generally  suffered.  Few 
maladies  occasion  more  discomfort  than  indigestion. 
When  one  must  always  ask  whether  this  or  that  article 
of  food  will  agree  with  him  or  give  him  pain,  a  great 
part  of  his  pleasure  in  life  is  gone,  and  it  is  no  wonder 
that  he  becomes  soured  in  disposition,  as  so  many  dys- 
peptics do.  Children  usually,  however,  have  strong 
digestive  organs,  and  the  boy  or  girl  who  will  eat  whole- 
some food  regularly  and  slowly  will  probably  have  good 
digestion  throughout  life.  The  use  of  too  much  food  or  of 
food  that  is  too  rich  is  likely  to  lead  to  lasting  discomfort. 

THE  HABIT  OF  USING  ALCOHOL 

Alcohol  and  Digestion.  —  Some  people  try  to  stimulate 
digestion  in  various  ways,  most  commonly  by  the  use  of 
alcoholic  drinks,  especially  wine.  But  it  is  a  mistake 
for  a  boy  or  girl  or  any  healthy  person  to  use  alcohol 
for  this  purpose.  It  does  not  aid  digestion  in  any  nor- 
mal individual.  In  this  connection  it  should  be  re- 
garded as  a  drug,  and  be  used,  if  at  all,  only  under 
medical  direction. 


70  PHYSIOLOGY   AND   HYGIENE 

Many  persons  use  alcoholic  drinks  for  this  or  some 
other  purpose  until  they  get  into  such  condition  that 
they  think  they  cannot  properly  digest  food  without 
using  wine  or  alcohol  in  some  form,  to  stimulate  the 
weakened  digestive  powers.  They  have  become  like  a 
horse  that  will  not  travel  without  a  whip.  The  con- 
tinued use  of  the  alcohol  is  very  likely  to  injure  the 
stomach  so  that  finally  proper  digestion  is  impossible. 
The  person  who  wishes  to  grow  up  strong  and  vigorous, 
with  healthy  digestive  organs,  will  let  alcoholic  drinks 
entirely  alone. 

The  Appetite  for  Alcohol.  —  There  is  one  character- 
istic of  all  alcoholic  drinks  that  makes  them  very 
dangerous.  If  a  person  eats  ordinary  foods,  such  as 
sugars  and  starches,  he  may  sometimes  eat  too  much ; 
but  this  does  not  develop  a  desire  for  larger  amounts 
of  the  food.  We  may  eat  enough  candy  to  make  us 
ill,  but  this  does  not  produce  a  craving  for  candy.  On 
the  contrary,  it  sometimes  even  causes  us  to  lose  all 
fondness  for  sweets,  at  least  for  a  time.  But  alcohol 
frequently  acts  in  a  different  way,  its  use  creating  a 
desire  for  more. 

The  first  glass  a  person  takes  is  generally  not  pleas- 
ing; but  if  he  continues  to  use  alcoholic  drinks,  after 
a  little  he  comes  to  enjoy  the  taste  and  the  effect,  and 
in  time  he  finds  that  he  has  a  craving  for  it,  and  feels  a 
certain  lack  if.  this  craving  is  not  satisfied.  Whereas  at 
first  a  small  amount  of  the  alcoholic  drink  was  all  he 
wanted,  he  soon  becomes  accustomed  to  this,  and  al- 
most without  knowing  it  he  takes  a  little  more.  This 


FOOD  HABITS  AND  COOKING  71 

later  fails  to  satisfy  him,  and,  not  realizing  how  serious 
a  matter  it  is,  he  increases  the  amount  of  alcohol  he 
uses,  sometimes  by  drinking  larger  amounts  of  weaker 
liquors,  and  sometimes  by  taking  stronger  ones.  And 
so  the  appetite  grows  until  he  finds  it  almost  impossible 
to  conquer  it.  In  other  words,  instead  of  being  a  free 
man  he  has  become  a  slave,  and  frequently  a  willing  slave, 
for  the  use  of  alcohol  regularly  and  in  large  amounts 
ordinarily  destroys  all  desire  to  live  a  healthful,  clean  life. 

In  most  cases  the  person  who  drinks  does  not  know 
that  the  appetite  is  growing  until  it  has  become  so 
strongly  fixed  as  to  do  him  great  injury.  In  just  this 
fact  lies  the  greatest  danger,  for  if  he  could  realize  how 
he  is  coming  under  the  influence  of  the  unfortunate 
habit,  he  would  break  it  before  it  mastered  him,  and 
before  it  destroyed  his  will  power.  When  that  is  gone 
the  best  of  the  person  is  lost. 

Now,  it  is  true  that  people  who  use  small  amounts 
of  alcohol  are  not  immediately  mastered  by  the  habit. 
But  it  is  equally  true  that  the  use  of  small  amounts 
of  alcohol  may  lead  to  the  development  of  an  appetite 
which  in  time  will  completely  master  the  user.  Habit- 
ual drunkards  are  made  out  of  boys  and  girls  who 
did  not  intend  to  use  alcohol  enough  to  injure  them. 
Unfortunately,  even  science  has  no  way  of  telling 
which  people  can  drink  alcohol  without  falling  under 
the  sway  of  its  appetite.  Strong  people,  as  well  as 
weak,  give  way  to  it.  The  moment  a  person  begins 
to  use  alcoholic  drinks,  even  in  a  mild  way,  he  places 
himself  in  the  class  of  people  from  whom  drunkards 


72  PHYSIOLOGY  AND   HYGIENE 

may  be  made.  The  only  safe  way  is  to  keep  as  far 
from  the  danger  as  possible,  by  letting  drink  abso- 
lutely alone. 

Intemperance  in  Eating  and  Drinking.  —  Although 
alcohol  is  likely  to  do  us  more  harm  than  any  other 
kind  of  drink  or  any  food,  still  we  should  be  careful  to 
avoid  all  forms  of  overindulgence.  We  may  injure  our- 
selves by  eating  too  much  candy  or  any  other  enjoyable 
food.  We  should  make  up  our  minds  to  be  moderate 
in  all  our  eating  and  to  avoid  alcoholic  drinks  alto- 
gether, for  in  this  way  only  can  we  insure  the  strong, 
healthful  growth  of  the  body,  and  only  thus  shall  we 
be  able  to  do  our  share  of  the  world's  work. 

PURPOSES  OF  COOKING 

No  one  who,  on  entering  the  house  tired  and  hungry 
after  a  half  day  at  school,  has  been  greeted  with  the 
appetizing  odors  coming  from  the  kitchen,  need  be 
told  that  cooking  has  its  advantages.  We  eat  very 
few  foods  without  cooking,  except  milk,  a  few  vege- 
tables, and  fruits.  Most  foods  are  not  considered  fit 
to  eat  until  they  are  cooked. 

There  are  three  purposes  in  cooking  food. 

1.  Cooking  develops  a  flavor.  —  We  have  only  to 
notice  the  difference  in  taste  between  raw  beefsteak 
and  the  same  steak  broiled  and  ready  for  the  table 
to  comprehend  how  cooking  improves  the  flavor.  It 
is  true  that  cooking  injures  the  flavor  of  certain  fruits, 
such  as  strawberries,  but  it  improves  the  taste  of  all 
meats  and  most  vegetables. 


FOOD   HABITS  AND  COOKING  73 

2.  Cooking  makes  food  easier  to  digest.  —  The  cooking 
of   vegetable  foods  is  usually  necessary  to  enable  us 
to  digest  them.     Potatoes,  for  example,  contain  large 
amounts  of  starch ;  but  it  is  shut  up  in  little  sacs  of  a 
kind  of  woody  substance,  as  shown  in  Figure  5,  and  so 
long  as  the  starch  is  in  these  sacs  the  digestive  juices 
cannot  get  at  it.     The  juices  have  little  or  no  power  to 
dissolve  the  sacs,  and  consequently  raw  potato  cannot 
be  digested.     Cooking  softens  the  woody  sacs  and  sets 
the  starch  free.     Moreover,  it  causes  the  starch  grains 
themselves  to  burst  and  when  burst  they  are  more  easily 
digested.     "We  should  remember  that  all  starchy  foods 
should  be  well  cooked  before  they  are  eaten.    The  cook- 
ing of  meats  is  not  of  great  importance  so  far  as  mere 
ease  of  digestion  is  concerned.     In  fact,  most  meats  are 
more  easily  digested  if  they  are  not  cooked  too  much. 

3.  Cooking  removes  danger  from  parasites.  —  Some  of 
our  foods  contain  minute  living  animals,  called  para- 
sites.    Some  of  these,  harmless  in  themselves,  throw  off 
products  which  are  poisonous ;   others  are  themselves 
dangerous,  and  might  do  us  considerable  injury  if  swal- 
lowed alive.     Pork,  especially,  sometimes  contains  large 
numbers  of  very  small  living  worms,  which,  if  taken 
into  our  bodies  alive,  are  likely  to  cause  serious  dis- 
ease, perhaps  death.      Pork  has   occasionally   another 
parasite   which   may  develop   in   the   human   stomach 
into  a  tapeworm  several   feet  long.       Heat   kills  the 
parasites,  and  pork,  including  ham,  should  therefore 
always  be  thoroughly  cooked.     Beef  and  mutton  are 
less  likely  to  contain  these  parasites,  but  neither  should 


74  PHYSIOLOGY  AND  HYGIENE 

be  eaten  uncooked.  We  have  already  learned  that  mill? 
is  frequently  cooked,  or  sterilized  as  we  say,  to  destroy 
any  disease  bacteria  it  may  contain. 

PRINCIPLES  OF  COOKING 

The  ambitious  girl  who  takes  pride  in  her  ability  to 
make  an  appetizing  cake  or  to  prepare  a  dinner  does 
not  need  to  be  taught  the  effect  of  cooking  on  the 
various  articles  of  food.  Neither  does  the  boy  who 
goes  camping  in  the  summer  and  gets  his  own  meals. 
Nevertheless,  there  are  certain  principles  underlying 
cooking  that  we  cannot  learn  over  stove  or  camp-fire, 
but  which  we  can  easily  understand.  We  have  already 
found  by  testing  the  white  of  an  egg  that  cooking 
coagulates  albumen.  We  know,  too,  from  boiling 
starch,  that  cooking  changes  starch  foods  into  pulpy 
masses.  Experience  in  the  kitchen  has  shown  us  that 
vegetables  are  softened  by  cooking,  and  that  fatty  sub- 
stances are  melted  or  made  liquid  by  the  same  process. 
In  general,  cooking  softens  foods  so  that  they  are  made 
easier  to  chew  and  to  digest.  Another  general  prin- 
ciple which  should  be  borne  in  mind  in  all  cooking,  is 
that  proteids  are  coagulated  by  heat.  This  is  especially 
important  as  related  to  beef  tea  and  soups. 

Beef  Tea.  —  If  raw  beef  is  cut  fine  and  soaked  in 
water,  a  part  of  the  nutritious  material  is  dissolved, 
and  the  liquid  is  good  food  as  it  stands.  But  if, 
after  the  beef  has  been  soaked,  the  liquid  is  boiled, 
all  of  the  dissolved  material  is  coagulated  and  appears 
as  a  brownish  scum.  This  can  be  separated  from  the 


FOOD   HABITS   AND   COOKING  75 

rest  by  straining  the  liquid  through  a  cloth.  Beef  tea 
is  usually  strained,  the  liquid  being  used  and  the  scum 
thrown  away.  Such  tea  is  pleasan-c  to  the  taste,  but 
after  the  scum  has  been  taken  off  it  contains  almost 
no  food.  Nothing  is  left  except  the  salts  and  flavors. 
These  are,  however,  frequently  of  use  to  invalids.  The 
salts  and  flavors  have  a  stimulating  action  on  the  diges- 
tive glands,  and  thus  assist  in  giving  the  sick  person 
an  appetite,  so  that  he  can  take,  and  more  easily  digest, 
real  food.  Beef  tea  is  therefore  of  use  in  sickness  or 
for  persons  with  weak  digestion ;  but  it  should  always, 
if  possible,  be  taken  together  with  something  more  sub- 
stantial. If  the  tea  were  made  of  finely  minced  beef  put 
into  cold  water  and  very  slowly  heated,  until  quite  hot, 
but  without  boiling,  it  would  be  very  nutritious,  for  it 
would  then  contain  the  food  material,  which  is  not  all 
coagulated  except  when  actually  boiled. 

Soups  and  Stews.  —  The  straining  out  of  the  food 
applies  also  to  the  making  of  soups  from  meats  and 
vegetables.  The  heat  of  boiling  produces  coagula- 
tion, and  the  clear  liquid,  which  is  strained  off  and 
served  as  the  soup,  contains  little  more  than  the  salts 
and  flavors.  Soups  are  not,  however,  usually  regarded 
as  foods.  They  are  served  at  the  beginning  of  a  meal 
as  a  slight  stimulant  to  digestion.  Stews,  on  the  other 
hand,  the  whole  cooked  mass  of  which  is  eaten,  are 
nourishing  and  useful  foods.  Though  the  proteid  has 
been  coagulated,  this  does  not  injure  the  stew  as  a  food, 
since  the  coagulated  material  as  well  as  the  liquid  is 
eaten0 


76  PHYSIOLOGY  AND   HYGIENE 

METHODS  OF  COOKING 

If  some  one  should  ask  us  how  our  mothers  cook, 
the  most  natural  answer  would  be,  "In  all  sorts  of 
ways."  The  answer  would  be  correct  in  a  certain 
sense,  and  yet  all  kinds  of  cooking  may  be  included 
under  the  four  heads  of  boiling,  baking,  broiling^  and 
frying. 

We  put  a  cover  on  top  of  the  kettle  of  boiling  meat 
to  hinder  the  escape  of  the  steam  and  the  odor.  Simi- 
larly, whenever  we  can,  we  put  a  cover  or  crust  around 
the  object  which  is  being  cooked,  to  keep  all  the  food 
material  and  flavors  inside.  This  may  be  done  by  heat- 
ing the  object  very  hot  when  the  cooking  begins.  Thus 
a  crust  is  formed  on  the  outside  of  the  loaf  of  baking 
bread.  The  high  heat  forms  a  similar  protective  coat 
around  the  meat  by  hardening  the  proteid  and  so 
keeping  the  juices  and  flavors  within. 

Boiling.  — Boiling  is  one  of  the  commonest  and  best 
methods  of  cooking,  although  it  does  not  produce  the 
finest  flavors  The  article  is  cooked  or  boiled  in 
water.  One  of  the  standing  rules  of  housekeeping  is, 
"  If  you  want  to  have  the  richness  in  the  liquid,  you 
must  put  the  article  into  cold  water  and  heat  slowly ; 
if  you  want  the  richness  in  the  article  itself,  it  must 
be  put  into  boiling  water."  So  vegetables  must  be 
dropped  into  boiling  water,  while  meat  for  stews 
should  be  put  upon  the  stove  in  cold  water.  If  the 
meat  is  placed  in  boiling  water,  a  coat  is  formed  on 
the  outside  at  once,  and  then  the  whole  may  be  allowed 


FOOD  HABITS  AND  COOKING  77 

to  simmer  over  the  fire  for  a  long  time  without  much 
further  loss.  Meat  cooked  thus  will  retain  its  juices 
and  have  an  excellent  flavor,  while  the  water  in  which 
it  is  cooked  will  contain  practically  nothing  of  value. 
The  liquid  of  the  stew,  on  the  other  hand,  is  to  be 
eaten  with  the  solid  matter,  so  the  meat  should  be 
placed  in  cold  water  and  then  allowed  to  simmer 
slowly,  in  order  that  the  liquid  may  contain  part  of 
the  food.  Stewing  is  an  economical  method  of  cook- 
ing, since  in  this  way  nothing  of  the  original  food  is 
lost. 

Baking  or  Roasting.  —  Baking  and  roasting  are  two 
good  methods  of  cooking  which  differ  slightly  from 
each  other,  but  are  similar  in  principle.  The  food 
is  cooked  in  hot  air,  either  in  an  oven  or  over  a  hot 
fire.  When  the  food  is  cooked  over  the  open  fire  we 
call  it  roasting ;  when  cooked  in  an  oven,  we  commonly 
speak  of  it  as  baking,  or,  in  the  case  of  meats,  we  call 
it  roasting.  As  the  heat  causes  the  liquid  juices, 
especially  of  meat,  to  ooze  to  the  surface,  it  is  best  to 
prevent  the  loss  of  these  juices  as  far  as  possible.  This 
is  done,  as  in  boiling,  by  heating  the  meat  very  hot  at 
the  beginning,  so  that  a  crust  may  be  formed.  The 
flavor  and  richness  of  the  meat  are  much  improved  by 
pouring  over  it,  say  once  in  every  fifteen  minutes,  the 
liquids  which  ooze  out,  a  process  called  basting.  If 
there  is  not  sufficient  liquid  for  this  purpose,  melted 
butter  or  suet,  or  even  salt  water  is  used.  In  baking 
bread  and  cake  it  is  also  desirable  to  use  high  heat  at 
the  start. 


78  PHYSIOLOGY  AND  HYGIENE 

Broiling.  —  One  of  the  quickest  and  most  desirable 
ways  of  cooking  is  broiling.  Especial  care  should  be 
taken  to  begin  the  cooking  over  a  very  hot  fire  in  order 
that  the  surface  of  the  meat  may  be  quickly  seared 
over,  and  the  juices  thus  kept  in  it. 

Frying.  —  Frying  is  a  method  of  cooking  very  com- 
mon, but  not  wholesome.  As  the  food  is  cooked  in  hot 
fat,  butter,  suet,  or  olive  oil,  it  is  apt  to  become  satu» 
rated  with  the  fat.  While  fat  of  itself  is  nutritious, 
food  soaked  in  it  is  very  difficult  to  digest.  To  fry 
with  the  least  injury  to  the  food,  there  should  be  an 
abundance  of  fat,  and  it  should  be  very  hot.  The  high 
heat,  as  in  other  methods  of  cooking,  forms  a  crust  on 
the  outside,  which  prevents,  in  considerable  measure, 
the  fat  from  getting  into  the  food. 

Yeast  and  Baking  Powder.  —  To  make  bread  we  mix 
flour  with  water,  or  milk,  add  yeast,  and  set  the  mix- 
ture in  a  warm  place  to  "rise."  The  yeast  grows  in 
the  bread,  producing  a  very  small  amount  of  alcohol 
and  a  gas  called  carbon  dioxide.  The  bubbles  of  gas 
appear  in  the  dough,  causing  it  to  rise  up  like  a  sponge. 
In  baking,  both  the  alcohol  and  the  gas  are  driven  off 
by  the  heat,  but  the  bread  is  filled  with  the  little  holes 
which  were  previously  occupied  by  the  carbon  dioxide. 
This  makes  the  bread  "light,"  and  easy  to  masticate 
and  digest.  Similar  bubbles  are  made  in  cake  and 
biscuit  by  putting  baking  powder  into  the  dough.  As 
baking  powder  produces  the  gas  very  quickly,  it  is 
adapted  to  rapid  baking.  To  develop  the  necessary  gas 
with  yeast  requires  that  the  dough  rise  for  several  hours. 


FOOD  HABITS  AND  COOKING  79 


QUESTIONS 

1.  Why  does  an  Eskimo  eat  fish  and  seal,  while  a  Chinaman 
eats  rice  ? 

2.  What  facts  should  be  considered  in  choosing  our  diet? 

3.  What  kinds  of  food  should  be  used  together? 

4.  When  should  we  eat? 

5.  Is  food  with  a  pleasant  taste  more  useful  to  the  body  than 
food  without  flavor  ?     Why  ? 

6.  How  can  we  best  enjoy  our  food? 

7.  Why  is  rapid  eating  unwise  ? 

8.  What  effect  has  alcohol  on  digestion? 

9.  How  is  an  appetite  for  alcohol  developed? 

10.  What  are  the  purposes  of  cooking  ? 

11.  How  does  cooking  make  a  potato  easier  to  digest? 

12.  What  does  cooking  generally  do  to  food  ? 

13.  Why  is  a  stew  nutritious  while  beef  tea  is  only  a  stimulant? 

14.  What  are  the  three  methods  of  cooking  ? 

15.  How  is  cooking  done  by  boiling  ? 

16.  How  is  food  cooked  by  baking  ? 

17.  Why  is  fried  food  apt  to  be  indigestible  ? 

18.  What  foods  may  properly  be  eaten  without  cooking? 

19.  What  do  yeast  and  baking  powder  do  to  food  ? 

20.  Why  is  plain  food  more  healthful  than  rich  food? 


CHAPTER  IV 
CIRCULATION 

EVERY  house  in  a  large  city  is  supplied  with  water 
from  faucets.  The  water  is  carried  to  the  house  by 
pipes  laid  in  the  ground,  and  the  pipes  come  from 
a  reservoir  which  supplies  the  whole  city.  In  many 
places  a  large  pump  near  the  reservoir  forces  the  water 
into  the  pipes.  If  the  pump  stops  working,  the  water 
throughout  the  city  ceases  to  run. 

We  have  seen  how  the  food  which  we  have  eaten 
gets  into  the  blood.  This  food  is  needed  in  all  parts 
of  the  body.  It  is  carried  to  the  arms,  the  head,  and 
the  various  organs  by  the  blood  vessels,  very  much  as 
the  city  is  supplied  with  water  by  the  water  pipes. 
The  blood  vessels  are  tubes  running  through  the  body, 
dividing  into  branches,  and  these  again  into  smaller 
branches,  so  that  every  organ  of  the  body,  no  matter 
how  small  it  may  be,  has  at  least  one.  The  heart  acts 
as  the  pumping  station,  and  by  it  the  blood  is  kept  in 
constant  motion. 

THE  BLOOD 

Let  us  see  what  this  liquid  is  which  flows  so  con- 
stantly through  the  blood  vessels.  We  already  know 
that  it  contains  the  part  of  the  food  we  have  eaten 

80 


CIRCULATION 


81 


which  has  been  dissolved  and  absorbed  from  the  intes- 
tines. But  it  has  in  it  other  materials  besides.  The 
blood  that  oozes  from  the  finger  when  we  have  a  cut 
looks  bright  red.  If,  however,  we  look  at  it  through  a 
microscope,  we  find  that  the  liquid  itself  is  almost  as 
clear  as  water.  In  fact,  the  liquid  part  of  the  blood, 
called  blood  plasma,  is  largely  water,  although  several 
substances  are  dissolved  in  it.  The  red  color  is  pro- 
duced by  millions  of  little  red  bodies  floating  about  in 
the  liquid.  These  minute  bodies  are  called  corpuscles. 
Red  Corpuscles.  —  The  most  prominent  of  the  solid 
bodies  in  the  blood  are  the  red  corpuscles.  These  are 


Plasma 


Corpuscle 


, 

Corpuscles 


FIG.  20.  —  A  LITTLE  BLOOD,  AS  IT  APPEARS  UNDER 
A  MICROSCOPE. 


shown  in  Figure  20.  They  are  small,  thin  disks,  cir- 
cular in  shape.  As  may  be  seen  from  (7,  they  are  slightly 
thinner  in  the  center  than  at  the  edge.  They  are  very 
small,  only  about  3^^  of  an  inch  in  diameter,  and 


82  PHYSIOLOGY  AND  HYGIENE 

consequently  they  are  invisible  except  through  a  micro- 
scope. They  are  present  in  the  blood  in  immense  num- 
bers, there  being  some  5,000,000  of  them  in  a  very  small 
drop.  Each  red  corpuscle  contains  a  red  substance 
called  hemoglobin.  The  important  work  performed  by 
the  red  corpuscles  we  shall  study  in  a  later  chapter. 

White  Corpuscles.  —  The  white  corpuscles  act  as  the 
street-cleaners  in  the  body.  They  are  fewer  in  num- 
ber than  the  red  corpuscles.  They  are  transparent, 
and  of  a  slightly  bluish  appearance.  They  have  no 
definite  shape,  and  in  fact  they  are  changing  shape 
constantly,  although  they  are  most  commonly  some- 
what spherical,  as  shown  in  Figure  20.  All  the  cor- 
puscles, both  white  and  red,  flow  through  the  blood 
vessels  with  the  blood.  The  red  corpuscles  can  go  only 
where  the  blood  carries  them;  but  the  white  corpuscles 
sometimes  crawl  out  of  the  blood  vessels  entirely,  push- 
ing their  way  through  the  walls.  They  then  travel 
around  independently  among  the  muscles  and  various 
parts  of  the  body.  There  they  catch  and  carry  off 
any  minute  irritating  substances  which  might  produce 
trouble  and  perhaps  disease,  if  allowed  to  remain.  Thus 
the  white  corpuscles  of  the  blood  are  believed  to  have 
a  very  important  part  in  warding  off  certain  diseases. 

WHAT  MAKES  THE  BLOOD  FLOW 

The  Heart.  — The  heart  is  situated  in  the  chest  a  little 
below  the  neck  and  slightly  on  the  left  side,  where,  as 
we  know,  its  beating  may  be  felt.  In  an  adult,  the 
heart  is  about  the  size  of  a  man's  fist,  and  is  somewhat 


CIRCULATION 


83 


pear-shaped,  as  shown  in  Figure  21.  When  in  the  nat- 
ural position,  the  apex,  or  small  end,  is  turned  down- 
ward and  a  little  to  the  left.  As  long  as  a  person  lives, 
his  heart  continues  to  pump  the  blood  through  his  blood 

vessels,   so   that   the 

To 


motion  of  the 
and  of  the 
never  ceases. 
a  pump,  the 


blood 
heart 
Like 
heart 


To  Arm 


To  Arm. 


Left. 
Auncfo 


has  tubes  entering  it  /    iMZM^IfibL  (Aorta) 

on  one  side  bringing 
the  blood  in,  and 
others  on  the  oppo- 
site side  carrying  the 
blood  away  from  it. 
The  blood  vessels 
bringing  blood  to 
the  heart  are  called 
veins ;  those  carry- 
ing it  away  are  called 
arteries.  In  Figure 
22  (facing  p.  84)  the 
arteries  are  colored 
red,  the  veins,  blue. 

If  we  cut  open  the 
heart   of   some  large 

animal,  such  as  a  sheep  or  an  ox,  we  shall  find  that, 
like  the  human  heart,  it  contains  four  cavities,  as 
shown  in  Figures  23  and  24.  The  two  cavities  on  the 
right  side,  called  the  right  auricle  and  right  ventricle, 


"Aorta 


FIG.  21. — THE  HEART. 
Showing  the  veins  and  arteries  con- 
nected with  it. 


84 


PHYSIOLOGY  AND  HYGIENE 


FIG.  23.  —  THE  RIGHT  SIDE  OP 
THE  HEART. 


are  connected  with  each  other.  The  two  on  the  other 
side,  the  left  auricle  and  the  left  ventricle,  are  also  con- 
nected with  each  other  There  is  no  connection  be 

tween    the   two   sides   of 
the  heart ;  the  blood  can 
not  flow  directly  from  one 
side  to  the  other. 

As  the  heart  beats, 
blood  which  has  just  com- 
pleted the  round  of  the 
body,  and  is  full  of  im- 
purities which  it  has 
gathered,  flows  into  the 
right  auricle  through  the 
large  veins  from  the  head 

and  body,  indicated  in  Figure  23,  and  fills  both  the  right 
auricle  and  the  right  ventricle. 
Then  the  heart  contracts,  that 
is,  the  muscles  of  the  walls  press 
the  blood  out,  as  we  squeeze  the 
juice  out  of  a  lemon  by  closing 
the  hand  tightly  about  it.  When 
the  heart  contracts,  the  blood 
forces  its  way  into  the  pulmo- 
nary artery,  shown  in  Figure  23. 
The  pulmonary  artery  carries  it 
to  the  lungs  to  be  purified. 

From  the  lungs  the  purified 
blood  comes  back  to  the  heart  again,  this  time  by  veins 
which  send  it  into  the  upper  of  the  two  chambers  at 


Aorti 


FIG.  24.  —  THE  LEFT  SIDE 
OF  THE  HEART. 


CIRCULATION  85 

the  left  side  of  the  heart,  that  is,  into  the  left  auricle ; 
thence  it  goes  to  the  left  ventricle,  as  shown  in  Figure  24, 
and  by  this  it  is  sent  through  the  large  artery  (the  aorta, 
Figs.  22  and  24)  in  all  directions  through  the  body.  Thus 
every  time  the  heart  beats,  one  side  of  it  takes  blood  in  \ 
from  the  head  and  body,  sending  it  to  the  lungs,  and  at  \ 
the  same  time  the  other  side  of  the  heart  takes  blood 
in  from  the  lungs  and  sends  it  out  through  the  body0        / 

In  order  to  keep  the  blood  flowing  in  the  right  direo  / 
tion  and  to  prevent  its  flowing  .backward,  the  heart  con- 
tains several  valves.  These  are  folds  inside  the  heart. 
When  open,  as  in  Figure  23,  they  allow  blood  to  pass 
freely  in  the  direction  indicated  by  the  arrow;  when 
lifted,  as  in  Figure  24,  they  completely  close  the  opening 
between  the  auricle  and  the  ventricle  and  prevent  blood 
from  being  forced  back  into  the  auricle  when  the  ven- 
tricle contracts.  As  soon  as  the  heart  relaxes,  they 
open  again  and  allow  the  ventricle  to  fill  up  once  more. 
There  are  also  some  valves  called  semilunar  valves 
(shown  in  Fig.  23),  which  in  a  similar  way  prevent 
blood  from  flowing  back  from  the  artery  into  the  heart. 

The  Beating  of  the  Heart.  —  The  heart  never  seems  to 
get  tired.  All  day  and  all  night  our  whole  lives  through 
it  keeps  at  its  work  of  pumping  the  blood.  The  heart 
of  a  grown  person  beats  about  seventy  times  a  minute, 
that  of  a  child  somewhat  faster.  It  spends  about 
three  tenths  of  a  second  in  beating,  and  then  rests 
for  four  tenths  of  a  second.  In  this  way  it  really 
works  less  time  than  it  rests,  only  instead  of  working 
in  the  daytime  and  resting  at  night,  like  the  body  in 


86  PHYSIOLOGY  AND   HYGIENE 

general,  it  does  a  bit  of  its  work  and  then  rests.  In 
this  way  it  is  able  to  keep  beating  without  becoming 
worn  out.  When  we  are  in  good  health  the  heart  beat 
is  strong  ;  it  weakens  when  we  are  ill. 

One  reason  why  the  use  of  tobacco  and  alcohol  is 
injurious  is  that  they  are  likely  to  weaken  the  proper 
action  of  the  heart.  Both  alcohol  and  tobacco  are  very 
likely  to  cause  heart  difficulties,  particularly  if  used 
by  young  people.  Nearly  every  boy  knows,  from  his 
own  observation,  that  neither  the  habitual  smoker  nor 
the  youth  who  uses  alcohol  wins  in  the  athletic  contest. 

The  Pulse.  —  When  a  stone  is  thrown  into  a  pond,  the 
water  is  disturbed  in  the  form  of  a  circular  wave  which 
grows  larger  and  larger,  but  all  the  time  lessens  in 
height,  until  it  disappears.  A  somewhat  similar  effect 
is  produced  by  the  heart  as  it  forces  the  blood  into  the 
arteries.  The  wave  of  pressure  produced  by  the  heart 
is  felt  all  through  the  arteries,  though  it  is  less  strong  the 
farther  it  is  from  the  heart.  The  wave  causes  a  slight 
swelling  of  the  arteries  as  the  blood  passes.  The  artery 
at  the  wrist  is  so  near  the  surface  that  we  can  feel  the 
wave,  known  as  the  pulse. 

The  pulse  can  be  found  in  any  of  the  arteries  where 
they  are  near  the  surface;  but  as  most  of  them  are 
deep  in  the  muscles,  there  are  few  places  where- we  can 
feel  the  throbbing.  The  usual  place  for  testing  the 
pulse  beat  is  at  the  wrist,  but  it  can  be  felt  at  the  neck, 
just  under  the  lower  jaw,  and  also  at  the  temples.  By 
feeling  of  the  pulse  the  physician  can  obtain  consider- 
able information  regarding  the  general  condition  of  the 
patient's  health. 


CIRCULATION  87 

BLOOD  VESSELS 

Arteries.  —  When  the  blood  is  forced  out  of  the  heart 
from  the  left  ventricle  it  passes  into  the  large  artery 
shown  as  red  in  Figure  22.  This  serves  as  the  main 
artery  to  supply  the  body.  The  artery  bends  over  to 
the  left  and  runs  down  the  body,  giving  off  several 
branches  on  its  way.  The  first  branches  extend  to  the 
head  and  the  arms,  while  others  lead  to  the  stomach 
and  the  intestines,  and  still  others  run  down  into  the 
legs.  This  main  artery  thus  supplies  blood  to  all  parts 
of  the  body,  just  as  the  water  main  furnishes  water 
for  every  house.  The  farther  the  branching  arteries 
are  from  the  heart  the  smaller  they  become,  until  finally 
each  is  divided  into  thousands  of  minute  tubes  which 
enter  every  organ  of  the  body. 

Capillaries.  —  If  we  should  follow  up  a  single  one  of 
the  minute  branches  of  an  artery,  we  should  find  that  it 
ends  in  a  set  of  even  smaller  tubes,  like  those  shown  in 
Figure  25.  These  are  called  capillaries.  The  capillaries 
are  too  small  to  be  seen  except  with  the  aid  of  a  micro- 
scope. They  divide  into  many  branches  which  come 
together  in  a  somewhat  irregular  manner,  differing  in 
different  localities,  as  shown  in  the  figure.  The  blood 
flows  from  the  small  arteries  into  these  capillaries,  and 
it  is  here  that  the  food  materials  held  in  solution  are 
given  up  to  the  living  parts  of  the  body.  Every  part 
of  the  body  is  filled  with  capillaries,  and  through  them 
each  part  gets  its  share  of  food  from  the  blood. 

We  must  remember  that  the  blood,  whether  in  the 


88 


PHYSIOLOGY  AND  HYGIENE 


arteries,  or  in  the  veins,  or  in  the  tiny  capillaries,  is 
always  flowing  in  closed  tubes.  It  never  empties  into 
the  tissues,  but  passes  to  them  through  the  delicate 
walls  of  the  capillaries.  Only  the  liquid  part  passes 
through,  the  corpuscles  remaining  in  the  blood  vessels. 
Veins.  —  A  four-track  railroad  usually  has  two 
tracks  for  the  trains,  say  from  Chicago,  and  two  for 

the  trains  going  to 
Chicago.  Let  us  say 
that  the  two  tracks 
from  the  railroad 
center  represent  the 
arteries  which  take 
the  blood  away  from 
the  heart.  After  its 
journey  through 
smaller  arteries  or 
branch  roads,  and 

through     the    capil- 
Showing  their  method  of  branching   The   larieg       Qr      g witches 
figure  on  the  right  shows  capillaries  in 
the  skin  ;  on  the  left,  capillaries  in  the   where    it    leaves   the 

muscles-  food,  the  blood  is 

ready  to  go  back  to  the  heart  on  the  return  tracks. 

The  little  capillary  branches  combine  into  larger 
tubes  or  blood  vessels  called  veins,  which  carry  the 
blood  back  to  the  heart.  The  veins  in  turn  combine, 
and  the  nearer  they  get  to  the  heart  the  larger  and  the 
fewer  in  number  they  become.  Finally  they  unite  into 
two  large  veins,  which  pour  all  the  blood  back  into  the 
heart.  Figure  22  B  shows  the  connection  of  the  heart 


FIG.  25. —  CAPILLARIES. 


CIRCULATION 


89 


•**  ^ 


with  these  veins.  With  the  next  beat  after  the  blood 
has  been  poured  into  the  heart  from  the/veins,  it  is 
pumped  out  again,  and  sent  once  more  on,  its  circuit  to 
the  lungs  and  around  the 
body.  The  general  arrange- 
ment of  the  heart,  arteries, 
capillaries,  and  veins  may  be 
understood  from  Figure  26. 

The  whole  process  of  ci 
culation,  as  it  is  called, 
like  what  would  happen  if 
all  the  water  that  flows  from 
our  water  faucets,  and,  after 
being  used,  is  thrown  into 
our  sinks,  were  carried  back 
to  the  reservoirs,  there  to 
be  thoroughly  purified,  and 
sent  out  once  more  to  the 
various  houses. 

All  of  the  arteries,  except 
those    going  to  the    lungs, 

carry  pure  blood,  while  the  FIG.  26.  — A  DIAGRAM  SHOWING 

,1  '  THE  GENERAL  CIRCULATION. 

veins,  except  those  coming 

The  blood  flows  in  the  direction 
from    the   lungs,   carry  im-  of  the  arrows. 

pure  blood.    The  pure  blood 

becomes  impure  as  it  takes  up  waste  material  in  the 

capillaries,  as  explained  in  a  later  chapter. 

The  arteries  are  embedded  deeply  in  the  flesh  ;  the 
veins  are  nearer  the  surface.  A  cut  in  the  flesh  is 
almost  sure  to  sever  one  or  more  small  veins,  but 


90  PHYSIOLOGY  AND  HYGIENE 

unless  it  is  very  deep  the  arteries  will  not  be  injured. 
The  blue  lines  appearing  on  the  back  of  the  hand, 
when  the  hand  is  allowed  to  hang  downward,  show 
the  positions  of  the  veins. 

HOW  THE  BLOOD  FLOWS 

Most  of  us  are  familiar  with  some  form  of  pump. 
We  have  noticed  that  the  water  flows  out  of  the  spout 
in  spurts ;  but  if  it  is  allowed  to  pass  for  some  distance 
through  a  trough  or  along  the  ground,  it  flows  as 
steadily  as  if  it  had  come  from  the  pump  in  a  contin- 
uous stream.  The  movement  of  the  blood  in  our 
bodies  is  similar.  The  heart  sends  the  blood  into 
the  main  artery  in  spurts,  pumping  it  with  force,  just 
as  the  pump  forces  water  into  the  trough.  As  the 
blood  goes  farther  and  farther  from  the  heart,  it  flows 
along  more  quietly,  until,  by  the  time .  it  has  passed 
through  the  capillaries  and  is  on  the  home  trip  through 
the  veins,  the  spurting  has  ceased  entirely. 

When  the  heart  beats,  it  forces  more  blood  into  the 
arteries  than  can  easily  flow  through  them.  Instead  of 
being  stiff,  however,  like  iron  water  pipes,  the  arteries 
are  elastic  like  India  rubber.  The  blood  flowing  into 
them  in  spurts  causes  the  arteries  to  stretch,  so  that 
it  flows  more  smoothly  than  it  would  if  flowing  in 
similar  spurts  through  iron  pipes. 

Bleeding.  —  The  blood  is  pumped  into  the  arteries 
with  so  much  force  that  it  flows  out  very  rapidly  in 
strong  jets  if  an  artery  is  cut  or  broken.  The  bleed- 
ing must  be  stopped  quickly,  or  the  person  may  bleed 


CIRCULATION 


91 


•Artery 


to  death.  The  veins,  on  the  other  hand,  do  not  become 
stretched,  since  the  blood  flows  in  them  with  less  force. 
If  a  vein  is  cut,  the  bleeding  is  not  so  rapid  as  from  a 
severed  artery,  and  it  is  not  so  dangerous.  But  in 
any  case  the  bleeding  must  be  stopped,  for  even  a 
small  wound  in  a  vein  would  cause  death  if  the  flow 

of    blood    were 

not  checked. 
Many  of  the 

most      common 

accidents  to 

which    we    are 

liable     produce 

bleeding.  If  the 

wound  is  only  a 

slight  break  or 

a     cut     in    the 

skin,  the  bleed- 
ing will  not  be 

serious.     We 

need     only     to 

bring  the  edges 

together  and 

bind  the  cut  or  other  wound  some- 
what tightly  with  a  cloth  or  a  bit 
of  adhesive  plaster,  and  the  bleed- 
ing soon  stops.     Even  wounds  which  are  comparatively 
deep  will   usually  stop  bleeding,  if   they  are  tightly 
bound  and  held  quiet  for  a  time. 
Bleeding  from  Arteries.  —  An  artery  wound  is  more 


FIG.  27.  —  SHOWING 
THE  MAIN  ARTERY 
OF  THE  ARM. 


FIG.  28.  —  SHOWING 
THE  MAIN  ARTERY 
IN  THE  LEG. 

In  front  of  the  leg 
above  the  knee,  but 
behind  it  below  the 
knee. 


92  PHYSIOLOGY  AND  HYGIENE 

serious,  and  must  be  treated  promptly  in  order  to  save 
the  person's  life.  If  a  cut  or  wound  of  any  sort  is 
followed  by.  a  forcible  spurting  of  blood,  it  is  certain 
that  an  artery  has  been  cut.  The  only  way  to  stop  the 
bleeding  is  to  compress  the  artery  above  the  cut,  that 
is,  between  the  cut  and  the  heart.  Severed  arteries  are 
most  common  in  the  arms  and  the  legs,  and  the  treat- 
ment in  such  cases  is  simple.  Figures  27  and  28 
show  the  course  of  the  chief  arteries 
in  the  arm  and  the  leg.  Figure  29 
shows  a  simple  method  of  grasping 
the  arm  so  as  to  compress  the  artery 
and  stop  the  bleeding,  temporarily, 
anywhere  in  the  arm  below  the 
elbow. 

The  easiest  and  most  effectual 
method  of  stopping  the  flow  is, 
however,  to  put  a  bandage  or  liga- 
ture around  the  arm  above  the  cut, 

FIG.    29.  -  SHOWING    and    to    PlaC3    a    stick   inside    ^    as 

HOW    TO    COMPRESS    indicated  in  Figure  30.     The  stick 

BREEDING.  T°  ST°P  is  then  to  be  turned'  twisting  the 
bandage,  and  binding  the  arm 
more  and  more  tightly,  until  the  bleeding  stops. 
If  a  stone  or  a  tightly  rolled  handkerchief  is  placed 
under  the  ligature  and  over  the  artery,  less  pressure  is 
required.  A  physician  must  then  be  summoned  as  soon 
as  possible.  The  ligature  must  be  kept  in  position 
until  the  physician  can  tie  the  artery  and  prevent 
further  bleeding.  With  a  wound  in  the  leg  the 


CIRCULATION 


93 


•/-Cut 


method  of  stopping  the  flow  of  blood  is  similar. 
Prompt  action  is  of  supreme  importance  in  all  such  cases. 
Why  the  Bleeding  stops.  —  If  there  is  a  break  in  the 
water  pipe  laid  along  a  city  street,  the  water  continues 
to  flow  out  until  the  workmen  have  repaired  the  pipe. 
The  leaking  would  never  stop 
of  itself.  How  is  it  then  that 
bleeding  from  a  vein  stops 
itself,  or  can  be  stopped,  so 
readily  ?  If,  whenever  there 
was  a  break  in  the  pipes,  the 
water  should  freeze  a  short 
distance  above  the  break,  the 
ice  would  close  up  the  open- 
ing and  stop  the  leak.  Some- 
thing of  this  sort  really  occurs 
in  the  case  of  a  wound.  The 
blood  does  not  freeze,  of 
course,  but  it  becomes  some- 
what solid ;  a  change  takes  FIG.  30.  —  SHOWING  THB 

-,  .         .,          i-i  n         METHOD     OF    APPLYING    A 

place    in    it    which    we    call      LlGATURE> 
clotting. 

Blood  Clotting.  —  Blood,  as  we  know,  is  a  liquid.  If 
blood  be  drawn  into  a  small  dish,  it  will  at  first  be 
liquid,  like  water.  But  if  it  is  allowed  to  stand  for  a 
few  minutes,  it  stiffens,  becoming  somewhat  jellylike. 
The  hardening  continues  until  the  blood  is  changed  into 
such  a  firm  jelly  that  it  will  not  flow  out,  even  if 
the  dish  is  turned  upside  down.  In  other  words,  the 
blood  has  clotted,  as  is  shown  in  Figure  31.  A  great 


94 


PHYSIOLOGY  AND   HYGIENE 


change  has  been  produced  in  the  nature  of  the  blood, 
and  after  clotting  it  would  naturally  be  of  no  further 
use,  as  it  could  no  longer  flow  through  the  blood  vessels. 
If  blood  is  taken  out  of  the  blood  vessels,  it  always 
clots  in  a  very  few  minutes,  no  matter  whether  it 
is  heated  or  cooled,  or  whether  it  is  brought  in  con- 
tact with  the  air  or  not.  So  long  as  it  remains  inside 


Clot 


Blood 


FIG.  31.  —  SHOWING  THE  CLOTTING  OF  BLOOD. 
At  A  it  is  liquid  ;  at  B  it  is  solid.    At  C  it  is  partly  liquid  again. 

the  blood  vessels  it  continues  in  liquid  form.  If,  how- 
ever, the  blood  vessels  themselves  are  injured  by  a  cut 
or  bruise,  the  blood  begins  to  clot  rapidly  near  the 
wound. 

From  this  fact  we  learn  how  bleeding  is  stopped. 
Whenever  a  bruise  or  a  cut  breaks  a  blood  vessel, 
the  wound  at  once  begins  to  bleed.  But  the  injury  to 
the  blood  vessel  causes  a  clotting  in  the  blood  near  the 
bruise,  and  the  clot  soon  closes  the  wound.  As  a  result, 


CIRCULATION  95 

any  ordinary  wound  soon  ceases  to  bleed;  but  if  there  is 
a  large  cut  through  a  vein  or  an  artery,  the  blood  may 
flow  out  so  rapidly  that  it  does  not  have  time  to  clot. 
In  such  cases  the  bleeding  must  be  stopped  by  a  ligature 
or  some  other  artificial  means. 

Effect  of  Gravity.  —  If  we  hold  the  hand  downward 
for  a  few  minutes,  it  becomes  red,  because  it  is  filled 
with  blood.  If,  on  the  contrary,  the  hand  is  held 
above  the  head,  it  turns  whiter.  This  shows  us  that 
the  blood  flows  down  more  easily  than  it  flows  up. 
Of  course,  the  blood  in  flowing  through  the  blood  ves- 
sels, is  pushed  on  by  the  force  of  the  heart.  Even 
when  the  blood  flows  downwards  into  the  legs,  it  must 
be  pushed  by  the  beating  heart.  But  the  weight  of 
the  blood  itself  has  some  influence  upon  its  flow,  helping 
the  heart  to  send  the  blood  down,  and  holding  back, 
more  or  less,  the  upward  flow.  The  aiding  and  checking 
of  the  flow  by  the  weight  of  the  blood,  or  gravity,  is, 
however,  of  no  practical  importance  except  under  cer- 
tain conditions,  such  as  fainting. 

Fainting.  —  Fainting  is  commonly  due  to  lack  of  suffi- 
cient blood  in  the  brain.  This  causes  unconsciousness. 
Recovery  from  the  fainting  fit  occurs  as  soon  as  the 
necessary  amount  of  blood  is  restored  to  the  brain. 
When  a  person  faints  it  usually  means  that  the  heart 
is  not  beating  vigorously  enough  to  force  the  blood 
upward  to  the  brain.  We  should,  accordingly,  assist 
the  heart  by  placing  the  head  of  the  patient  a  little 
lower  than  the  body.  This  will  help  the  blood  to  run 
into  the  head  from  its  own  weight.  The  return  of  blood 


96  PHYSIOLOGY  AND  HYGIENE 

to  the  brain  may  also  be  hastened  by  stimulating  the 
action  of  the  heart.  Dashing  a  little  cold  water  upon 
the  face  hastens  the  beating  of  the  heart,  helps  to  re- 
store the  blood  to  the  brain,  and  so  insures  recovery 
from  the  fainting  fit.  Our  natural  impulse,  when  a 
person  faints,  is  to  lift  his  head,  but  as  a  rule  this  will 
hinder  recovery. 

HOW  THE  FLOW  OF  BLOOD  IS  CONTROLLED 

Regulation  of  the  Heart  Beat.  —  The  circulation  of  the 
blood  is  produced  by  the  beating  of  the  heart,  and  at 
the  same  time  the  heart  is  partly  controlled  by  the 
brain.  The  heart  can  be  entirely  removed  from  the 
body  of  a  cat  or  a  dog  and  yet  it  will  continue  to  beat, 
sometimes  for  hours.  This  shows  that  the  heart-  is 
able  to  beat  independently  of  the  brain.  Nevertheless 
the  brain  has  the  power  of  hastening  and  checking  the 
heart's  action.  The  brain  is,  in  fact,  the  central  organ  of 
the  body,  and  as  such  it  controls  the  action  of  every  part. 

Passing  from  the  brain  to  the  heart  are  two  nerves 
which  serve,  like  telegraph  wires,  to  connect  the  two. 
Over  these  nerves  the  brain  is  constantly  sending  mes- 
sages to  the  heart.  Sometimes  the  heart  beats  more 
rapidly  than  is  necessary,  and  the  brain  sends  a  message 
which  checks  its  action  a  little  and  makes  it  beat  more 
slowly.  At  other  times  the  heart  does  not  beat  fast 
enough,  and  needs  to  be  hastened.  If  a  boy  starts 
to  run,  he  needs  to  have  an  extra  amount  of  blood 
sent  to  the  muscles.  Immediately  a  message  is  sent 
from  the  brain  that  sets  the  heart  to  beating  faster, 


CIRCULATION  97 

which,  of  course,  causes  the  blood  to  flow  more  rapidly. 
After  the  boy  stops  running,  another  message  causes 
the  heart  beat  to  become  gradually  slower  until  it 
reaches  the  ordinary  rate.  There  are  many  other 
occasions  when  a  quickened  heart  beat  is  desirable. 

In  every  case  of  need  responses  come  from  the  brain, 
and  the  heart  is  accordingly  controlled.  All  this  is 
done  without  our  being  conscious  of  it.  We  cannot  by 
will  power  change  the  rate  of  the  heart's  beating,  and 
usually  we  do  not  even  know  when  a  change  occurs. 

We  can  readily  test  the  difference  in  the  rate  of  the 
beating  by  counting  the  number  of  beats  a  minute, 

(1)  after  we  have  been  sitting  quietly  for  some  time, 

(2)  after  we  have  walked  up  a  flight  of  stairs  or  have 
run  for  some  distance,  and  again  (3)  after  fifteen  min- 
utes of  quiet. 

Regulation  of  the  Blood  Vessels.  —  The  flow  of  water 
from  the  city  water  pipes  is  regulated  in  two  ways. 
The  pump  may  work  more  or  less  rapidly  as  occasion 
demands ;  the  faster  its  movement,  the  greater  the 
amount  of  water  flowing  into  the  pipes.  This  action 
corresponds  to  the  changes  in  the  rate  of  the  heart  beat. 
The  flow  of  water  in  the  various  houses  depends  upon 
how  wide  we  open  the  faucet,  whether  to  its  full  extent, 
halfway,  or  not  at  all.  So  in  our  bodies  there  is  a 
means  of  changing  the  size  of  each  little  blood  vessel,  to 
allow  either  more  or  less  of  the  blood  to  pass  through. 

All  of  the  small  arteries  have  muscle  fibers  running 
around  them,  as  indicated  in  Figure  32.  When  these 
muscle  fibers  contract,  they  narrow  the  blood  vessel, 


98  PHYSIOLOGY  AND   HYGIENE 

lessening  the  amount  of  blood  allowed  to  pass.     When 
they  relax  again,  the  blood  vessel  opens  and  the  blood 

flows  in  a  larger 
stream.  These  mus- 
cle fibers  are  all  con- 
nected with  the  brain, 
or  the  spinal  cord,  by 
nerves  through  which 
they  can  be  made  to 
relax  or  contract.  In 

FIG.  32.  —  SECTION  OF  AN  ARTERY  AND     ,,  .  ,,       ,,  - 

A  VEIN  this  way  the  flow  of 


Showing  the  thick  elastic  wall  of  the      bl°°d  in  ^  Or^an  °f 
artery  and  the  thinner  wall  of  the  /ein.      the  body  can    be   in- 

creased or  decreased. 

If  for  any  reason  a  particular  part  of  the  body  needs 
more  blood  than  usual,  it  is  not  always  necessary  to 
increase  the  rate  of  the  heart  beat.  The  little  muscles 
around  the  arteries  simply  relax,  so  that  these  blood 
vessels  become  larger,  and  at  once  more  blood  flows 
through  them.  On  the  other  hand,  if  less  blood  is 
needed  in  a  certain  organ,  the  brain  causes  the  muscle 
fibers  to  contract,  so  as  to  close,  or  partly  close,  the 
blood  vessels. 

When  any  part  of  the  body  is  actively  at  work,  it 
needs  plenty  of  blood,  since  the  blood  brings  it  nourish- 
ment. The  more  vigorous  the  work,  the  greater  is  the 
amount  of  blood  needed.  The  brain  needs  an  extra  sup- 
ply when  we  think  hard,  the  leg  muscles  when  we  run. 

After  a  hearty  dinner  the  stomach  and  the  intestines 
need  a  large  amount  of  blood  for  the  work  of  digestion. 


CIRCULATION  99 

By  means  of  the  nerves  from  the  brain  (vaso-motor 
nerves,  they  are  called),  the  small  arteries  in  the  intes- 
tines are  made  to  relax  and  allow  the  blood  to  flow 
through  more  quickly  than  usual.  The  walls  of  the 
intestines  and  the  stomach  become  filled  with  blood, 
and  digestion  goes  on  rapidly. 

This  large  flow  through  the  intestines  necessarily 
draws  some  blood  from  the  brain  and  othe?  parts  of 
the  body.  Accordingly,  after  a  heavy  meal  most  people 
are  a  little  stupid  and  rather  inclined  to  sleep.  On 
the  other  hand,  when  a  person  is  studying  very  hard, 
so  that  the  brain  is  especially  active,  the  blood  vessels 
in  the  brain  itself  are  relaxed  to  allow  of  a  large  flow 
of  blood.  It  is  therefore  difficult  to  do  profitable 
studying  and  to  digest  a  heavy  meal  at  the  same  time. 
Either  the  brain  will  take  too  much  blood  to  allow  of 
good  digestion,  or  els6  the  stomach  and  the  intestines 
will  have  so  large  a  share  of  the  blood  that  tke  brain  is 
sluggish  and  the  lessons  suffer. 

Blushing  results  from  a  similar  action  of  the  blood 
vessels  in  the  skin  of  the  face ;  these  vessels  are  relaxed, 
and  allow  an  extra  amount  of  blood  to  flow  through 
them.  The  cheeks  become  thereby  red  and  warm.  On 
the  other  hand,  an  unusual  contraction  of  the  vessels 
in  the  face  causes  the  skin  to  become  pale.  A  flushed 
skin  thus  means  expanded  blood  vessels,  while  a  pale  or 
white  skin  means  contracted  ones. 

The  Feeling  of  Warmth  and  Cold.  —  The  expansion 
and  contraction  of  the  small  arteries  in  the  skin  cause 
our  feelings  of  heat  and  cold.  The  blood  is  warmer  in 


100  PHYSIOLOGY  AND  HYGIENE 

the  interior  of  the  body  than  at  the  surface,  but  since 
only  the  skin  feels  warm  or  cold,  we  do  not  notice 
the  warmth  of  the  blood  as  long  as  it  is  below  the  skin. 
When  we  exercise  vigorously,  as  in  running,  we  feel 
very  warm.  The  reason  is  that  the  exercise  causes  the 
blood  vessels  in  the  skin  to  expand  so  that  an  extra 
large  amount  of  blood  flows  through  them.  The  skin 
becomes  red  and  the  blood  so  warms  it  that  we  feel 
the  heat. 

Although  we  feel  especially  warm  when  the  blood 
flows  rapidly  through  the  skin,  the  body  is  in  fact  no 
warmer  than  usual.  Indeed,  the  sending  of  the  warm 
blood  through  the  skin  is  the  means  by  which  the  body 
cools  its  blood,  to  keep  us  from  really  becoming  warmer. 
If  the  body  seems  likely  to  become  too  warm,  it  sends 
blood  to  the  skin  at  once,  to  be  cooled  by  the  air.  But 
if  the  body  has  too  little  heat,  the  blood  vessels  con- 
tract, and  the  warm  blood  is  kept  away  from  the  sur- 
face, causing  pallor  of  the  skin.  The  skin  blood  vessels 
thus  serve  much  the  same  purpose  as  little  windows, 
which  are  opened  or  closed  to  regulate  the  temperature. 

Sometimes  we  are  deceived  by  the  feeling  of  warmth. 
Whenever  the  blood  vessels  in  the  skin  are  opened  wider 
than  usual,  so  that  warm  blood  flows  through  them,  we 
may  be  sure  we  are  cooling  off,  no  matter  how  warm  we 
feel.  Now  there  are  certain  substances  which,  if  taken 
into  the  stomach,  cause  the  blood  vessels  to  enlarge. 
For  example,  a  certain  amount  of  alcohol  causes  the 
skin  to  become  flushed  and  the  body  to  feel  warm. 
Many  people  believe,  therefore,  that  the  alcohol  has 


CIRCULATION  101 

actually  warmed  them,  and  so  they  take  it  on  a  cold 
day  to  keep  them  warm.  Exactly  the  opposite  is  the 
case.  The  alcohol  has  caused  the  blood  vessels  to 
expand,  or,  in  other  words,  it  has  opened  the  windows 
in  the  skin,  and  the  body  has  begun  to  cool.  The 
person  feels  warm  simply  because  the  skin  is  heated, 
but  he  is  really  losing  heat  more  rapidly  than  before. 
Arctic  explorers  find  that  they  cannot  endure  the 
extreme  cold  so  well  if  they  use  alcoholic  drinks. 

In  very  cold  weather  the  use  of  alcohol  would  only 
make  us  colder  if  we  were  going  out  of  doors  immedi- 
ately afterwards.  Sometimes  when  a  person  has  been 
overcome  with  cold  and  is  half  frozen,  and  perhaps  un- 
conscious from  the  exposure,  alcohol  is  given  to  quicken 
the  heart  action  temporarily  and  to  hasten  recovery. 
Under  such  circumstances  it  is  not  used  to  warm  the 
person,  but  as  a  drug  to  meet  an  emergency. 

SUMMARY  OF  THE  CIRCULATION  PROCESS 

Let  us  trace  briefly  once  more  the  journey  made  by 
the  blood,  beginning  when  it  enters  the  heart  after  a 
journey  around  the  body.  It  enters  the  right  auricle 
and  ventricle  of  the  heart  through  large  veins  coming 
from  the  head  and  body.  Then  it  is  forced  into  the 
pulmonary  artery,  which  carries  it  to  the  lungs  to  be 
purified.  From  the  lungs  it  returns  to  the  heart,  this 
time  entering  the  left  auricle  and  ventricle,  from  which 
it  passes  into  the  main  artery  of  the  body.  The  main 
artery  divides  into  branches  which  take  blood  to  the 
head,  the  limbs,  and  the  various  organs;  and  the 


102  PHYSIOLOGY  AND  HYGIENE 

branches  subdivide  into  smaller  and  smaller  branches 
which  finally  end  in  the  little  tubes  called  capillaries. 
There  the  pure  blood  gives  up  its  food,  and  at  the  same 
time  takes  up  the  waste  products. 

From  the  capillaries  the  impure  blood  enters  small 
veins  which  connect  with  larger  veins,  and  these  with 
still  larger  ones,  until  finally  all  unite  in  the  two 
large  veins  which  carry  the  blood  to  the  heart  once 
more. 

The  beating  of  the  heart  is  continuous,  but  the  rate 
can  be  increased  or  diminished  through  the  action  of  cer- 
tain centers  of  the  brain ;  blood  supply  of  any  organ  can 
be  increased  or  diminished  by  the  expansion  or  contrac- 
tion of  the  small  blood  vessels.  The  whole  circulation 
is  controlled  without  our  being  conscious  of  the  fact  or 
being  able  voluntarily  to  change  it  in  any  way. 

QUESTIONS 

1.  What  is  the  purpose  of  circulation  ? 

2.  Describe  the  red  blood  corpuscles. 

3.  What  is  the  use  of  the  white  blood  corpuscles? 

4.  What  is  the  duty  of  the  heart? 

5.  What  are  arteries  ?    Veins  ? 

6.  Do  any  of  the  arteries  carry  impure  blood  ? 

7.  How  can  we  tell  when  an  artery  is  cut?    What  should  be 
done  in  such  case  ?    Why  is  such  a  cut  more  serious  than  a  cut 
vein  ? 

8.  How  does  nature  stop  bleeding  from  wounds? 

9.  If  the  blood  would  not  clot,  what  would  happen  when  a  per- 
son is  cut  ? 

10.  What  is  the  pulse  ?  Why  does  a  physician  count  a  patient's 
pulse? 


CIRCULATION  103 

11.  What  are  the  capillaries  ? 

12.  What  is  fainting?    What  is  the  remedy  for  it? 

13.  How  is  the  flow  of  blood  regulated  ? 

14.  How  is  the  amount  of  blood  that  each  organ  receives  regu- 
lated? 

15.  Why  should  we  not  study  immediately  after  a  hearty  dinner  ? 

16.  If  a  person  should  run  rapidly  immediately  after  dinner, 
would  it  help  or  hinder  digestion?    Why? 

17.  Why  do  we  feel  warm  after  running? 

18.  Why  is  it  that  alcohol  makes  a  cold  man  feel  warmer?    Is 
he  actually  warmer? , 


CHAPTER  V 
RESPIRATION 

ONLY  as  the  fuel  inta  locomotive  is  burned  does  it 
drive  the  engine.  ^The  burning  of  the  fuel  is  really  a 
union  of  the  coal  with  a  certain  part  of  the  air  called 
oxygen.  The  process  is  oxidation,  and  it  produces  heat. 
As  a  result  of  the  burning,  a  large  amount  of  another 
gas,  carbon  dioxide,  is  produced,  which  passes  out  of 
the  smoke-stack  with  the  smoke,  and  there  is  left 
in  the  grate  a  quantity  of  ashes.  In  order  that  the 
fires  in  the  engine  may  be  kept  burning  brightly,  it  is 
necessary  that  there  be  a  supply  of  air.  This  is  fur- 
nished by  means  of  the  draft.  It  is  necessary  also 
that  the  gases  have  some  means  of  passing  off,  as  they 
do  through  the  smoke-stack.  The  ashes  must  also  be 
frequently  removed  from  the  grate  to  keep  the  fires 
free,  and  allow  the  air  to  reach  the  burning  coal. 

The  processes  which  take  place  in  our  bodies  are 
somewhat  similar  to  those  in  the  engine.  The  food  is 
oxidized,  although  the  process  differs  much  from  the 
burning  of  coal,  and  a  certain  amount  of  heat  is  pro- 
duced which  warms  the  body.  Oxygen  gas  from 
the  air  is  as  necessary  for  the  body  oxidation  as  for 
burning  the  coal.  What  is  more,  there  is  produced  in 
the  body  the  same  kind  of  gas  as  in  the  engine,  carbon 

104 


RESPIRATION  105 

dioxide,  and  a  certain  material  is  left  that  corresponds 
in  a  way  to  the  ashes,  and  of  this  the  body  must  dis- 
pose. How  the  body  gets  its  oxygen,  and  gets  rid  of 
its  carbon  dioxide,  is  a  story  in  itself.  This  exchange 
of  gases  between  the  air  and  the  blood  is  brought  about 
by  breathing,  or  respiration. 

THE  AIR  PASSAGES  AND  THE  LUNGS 

When  we  breathe  properly,  air  is  taken  in  at  the  nos- 
trils, and  after  passing  through  the  large  nasal  cavities 
above  the  mouth  enters  the  throat.  The  nostrils,  as  we 
saw  in  Figure  12,  lead  directly  to  the  throat,  so  that  the 
air  has  a  free  passage.  We  have  seen,  too,  that  the 
mouth  also  leads  directly  to  the  throat.  If  the  mouth 
is  open,  air  may  be  taken  through  it  even  more  easily 
than  through  the  nostrils.  In  either  case  the  air  passes 
directly  into  the  throat,  and  then  down  to  the  lungs. 

Mouth-breathing  is  not,  however,  the  natural  method 
of  taking  in  air,  and  is  always  injurious  if  continued 
for  any  length  of  time.  The  air  passes  much  more 
rapidly  through  the  mouth  than  through  the  nostrils, 
and  consequently  it  is  not  so  thoroughly  warmed  when 
it  reaches  the  lungs.  What  is  more,  the  dust  in  the  air 
is  not  so  completely  removed  as  when  it  passes  through 
the  nostrils.  The  narrow,  irregular  passages  of  the 
nose,  with  their  moist  surfaces  and  hairs,  hold  the  dust 
and  prevent  it  from  passing  into  the  lungs.  We  should 
carefully  avoid  getting  into  the  habit  of  breathing 
through  the  mouth,  even  when  walking  fast  or  when 
running,  lest  we  cause  throat  and  lung  troubles  that 


106  PHYSIOLOGY  AND   HYGIENE 

may  be  a  serious  menace  to  health.  If  a  person  should 
find  that  he  really  is  unable  to  breathe  excepting  with 
the  mouth  open,  it  indicates  that  something  is  wrong 
in  his  throat  or  nose,  and  he  should  be  examined  by  a 
physician. 

The  Windpipe  or  Trachea.  —  The  air  passes  from  the 
throat  into  the  windpipe  (see  Fig.  12).  This  is  a  large 
tube  at  the  front  of  the  neck.  As  we  have  seen,  it  is 
always  open,  except  that  at  the  instant  when  food 
is  being  swallowed  the  epiglottis  closes  down  over 
it  like  a  lid.  The  epiglottis  springs  up  again,  how- 
ever, as  soon  as  the  food  has  slipped  by,  to  allow  the 
free  passage  of  air  to  and  from  the  tube.  The  wind- 
pipe itself  is  held  open  by  a  series  of  hard,  cartilage 
rings  in  its  walls,  which  prevent  it  from  collapsing. 

Just  within  the  upper  end  of  the  windpipe  is  situated 
a  very  important  organ,  the  larynx.  If  we  place  our 
fingers  upon  the  outside  of  the  throat  just  below  the 
jaw,  we  can  feel  a  hard  bunch  move  up  and  down  as  we 
swallow.  This  bunch,  sometimes  called  the  Adam's 
apple,  is  the  larynx.  Figure  33  shows  its  location  at 
the  beginning  of  the  windpipe.  Inside  of  the  larynx 
are  the  so-called  vocal  cords,  by  means  of  which  we  are 
able  to  make  sound  when  talking.  Below  the  larynx 
the  windpipe  passes  down  through  the  neck  in  a 
straight  line  and  enters  the  chest,  where,  as  shown  in 
Figure  33,  it  divides  into  two  branches. 

The  Lungs.  — When  the  windpipe  divides,  one  branch 
enters  one  of  the  lungs,  and  the  other  branch  enters  the 
other  lung.  The  lungs  look  like  two  elastic  bags,  as 


RESPIRATION 


107 


indicated  in  Figure  33,  and  are  capable  of  being  dis- 
tended when  air  is  drawn  in,  and  of  collapsing  when 
the  air  is  expelled.  Each  of  the  bags  seems  to  be  filled 
with  a  mass  of  spongy  material,  which  is  made  up  prin- 


FIG.  33.  —  THE  LUNGS. 

Upon  the  left  is  shown  the  lung  from  the  outside; 
upon  the  right  the  lung  is  opened  to  show  the 
branches  of  the  air  tubes. 

cipally  of  air  tubes,  air  cells,  and  blood  vessels.  Each 
branch  of  the  windpipe,  on  entering  the  lung,  divides 
into  numerous  smaller  branches.  Each  of  these  divides 


108  PHYSIOLOGY  AND  HYGIENE 

again,  and  so  the  division  continues,  until  finally  the 
smallest  of  the  branches  form  a  system  of  very  minute 
tubes  similar  in  its  irregular  divisions  to  the  twigs  of  a 
tree.  The  whole  lung,  in  fact,  appears  somewhat  like 
a  tree  with  the  branches  upside  down.  Each  twig  ends 
in  a  small  rounded  sac  or  air  chamber.  The  air  taken 
in  through  the  nostrils  finally  enters  and  expands  these 
little  chambers,  which  are  shown  in 
Figures  33  and  34.  The  lungs 
contain  many  thousands  of  the 
sacs,  and  every  time  we  breathe 
they  expand  with  the  air  which 
they  take  in.  Thus  the  whole  lung, 
being  filled  with  air,  is  light  and 
FIG.  34.  —AIR  SACS,  spongy.  It  is  an  excellent  plan 


Found  at  the  ends  of  the  to  ^raw  several  long  breaths  every 
air  tubes  in  the  lungs.    ,  . 

little  while,  to  distend  the  air  sacs 

as   much   as   possible,   thus    "clearing  the   lungs"   as 
we  say. 

Blood  Vessels  of  the  Lungs.  —  We  have  already  learned 
that  the  right  side  of  the  heart  receives  the  impure 
blood  and  sends  it  through  the  pulmonary  artery  to  the 
lungs.  When  this  artery  enters  the  lungs  it  divides 
and  subdivides  into  small  blood  vessels,  which  in  turn 
divide  into  very  small  capillaries.  The  capillaries  are 
wrapped  around  the  air  sacs,  appearing  like  a  sort  of 
net  about  them  (Fig.  35).  While  the  blood  from 
the  heart  is  flowing  through  the  capillaries  it  is  very 
close  to  the  air  which  fills  the  sacs.  It  is  so  close,  in 
fact,  that  it  takes  some  of  the  oxygen  out  of  the  sacs, 


RESPIRATION 


109 


giving  up  to  them  in  exchange  the  impure  gases  which 
it  holds.  After  leaving  these  gases  and  taking  the 
oxygen,  the  blood  is  purified  and  ready  to  go  back  to 
the  heart. 

HOW  AIR  IS  DRAWN  INTO  THE  LUNGS 

When  the  handles  of  a  pair  of  bellows  are  extended 
the  cavity  inside  is  enlarged,  and  air  is  sucked  in  to  fill 
the  increased  space. 
If  a  rubber  ball  with 
a  hole  in  it  is  com- 
pressed until  it  col- 
lapses, and  is  then 
held  in  a  dish  of 
water  and  allowed 
to  take  its  normal 
shape,  the  hollow 
fills  with  water. 
Breathing  is  based 
upon  a  similar  prin- 
ciple. The  air  is  FIG.  37.  —  SHOWING  THE  CHEST  WITH  THB 
forced  into  the  LuNG*  AND  HEART  IN  Po8ITION  BEHIND 

THE    JilBS. 

lungs  in  much  the 

same  way  that  bellows  are  filled  with  air  and  the  ball 

is  filled  with  water. 

The  Chest  or  Thorax. — The  lungs  are  inclosed  in  a 
box  called  the  chest.  This  is  closed  in  front,  at  the 
sides,  and  at  the  top  by  the  ribs,  muscles,  and  skin. 
Figure  37  shows  the  chest  and  the  position  of  the  lungs. 
At  the  rear  the  chest  is  closed  by  the  backbone  and 


110 


PHYSIOLOGY  AND  HYGIENE 


the  ribs.  A  thin  muscular  partition,  the  diaphragm, 
stretches  across  the  bottom,  shutting  the  box  up  com- 
pletely. The  windpipe  is  the  only  opening  in  the  chest 
for  the  entrance  of  air. 

The  position  which  the  diaphragm  would  take  if  left 
to  itself  is  that  of  a  slight  upward  curve,  as  shown  in 

Figure  38.  Each  time  we 
draw  in  a  breath,  the  muscles 
of  the  diaphragm  shorten  and 
draw  it  down  to  the  posi- 
tion shown  by  the  dotted  line 
in  Figure  38.  This  enlarges 
the  space  in  the  chest,  and 
the  outside  air,  rushing  in 
through  the  nostrils  and  the 
windpipe,  enters  the  lungs, 
and  fills  the  enlarged  space. 

The  diaphragm  is  helped 
by  the  ribs  in  making  the 
space  within  the  chest  larger. 
The  ribs,  in  their  usual  posi- 
tion, tend  to  bend  downward. 
As  we  breathe,  the  numerous 
muscles  surrounding  the  ribs 


FIG.  38.  —  SHOWING  THE  MOVE-  raise  them  upward  and  f  or- 


MENT  OP  THE  DIAPHRAGM  IN  ward,  increasing  considerably 

BREATHING. 

The  dotted  line  represents  the  the  space  within.    The  dotted 
position    at   the   end   of   an  lines  in  Figure  39  show  the 

position  of  the  ribs  when  the 
Air  is  drawn  in   when  we   breathe  ; 


inhalation. 
lungs  are  full. 


RESPIRATION 


111 


when  the  cavity  of  the  chest  is  enlarged,  the  pressure 
of  the  air  forces  it  in  to  fill  the  enlarged  cavity,  much 
as  air  is  forced  into  a  pair  of  bellows. 

After  the  lungs  are  thus  filled  with  air,  the  muscles 
relax,  and  the  ribs  fall  of  their  own  weight  into  the 
position  shown  in  the  solid 
lines  of  Figure  39.  At  the 
same  time  the  diaphragm  re- 
laxes, and  is  pushed  up  to 
its  former  position.  This  is 
chiefly  accomplished  by  the 
pressure  of  the  organs  below, 
which  it  had  compressed.  Both 
motions  decrease  the  size  of 
the  chest  cavity,  and  the  air 
is  squeezed  out  exactly  as 
the  air  is  forced  from  the  bel- 
lows by  the  pressure  on  the 
handles.  Drawing  the  air  into 
the  lungs  is  called  inspiration 
or  inhalation.  Forcing  the  air 
out  by  contraction  is  called 
expiration  or  exhalation.  The 
whole  process  is  controlled 
through  nerves  by  the  brain. 

Capacity  of  the  Lungs.  —  A 
certain  amount  of  air  is 
drawn  into  the  lungs  with  each 

breath,  and  about  the  same  amount  forced  out.  But 
the  lungs  are  never  completely  filled  by  an  ordinary 


FIG.  39.  —  SHOWING  THE 
MOVEMENT  OP  THE  KIBS 
IN  BREATHING. 


112  PHYSIOLOGY  AND  HYGIENE 

breath,  nor  are  they  ever  completely  emptied  after  the 
exhalation.  After  taking  an  ordinary  breath  we  can 
still  breathe  in  more  air  by  an  additional  deep  breath, 
and  after  an  ordinary  exhalation  we  can  expel  more  air 
by  an  effort.  Thus  in  ordinary  breathing  we  change 
only  a  part  of  the  air  in  the  lungs.  In  fact,  the  lungs 
of  a  grown  person  commonly  hold  about  350  cubic 
inches  of  air,  of  which  only  about  30  inches  are  changed 
with  each  ordinary  quiet  breath.  We  might  renew 
most  of  the  air  by  very  rapid  and  very  deep  breathing, 
but  to  do  so  continuously  would  be  too  great  an  effort. 

Lung  Exercise.  —  The  lungs  should  by  all  means  be 
completely  filled  with  pure  air  occasionally.  If  the  air 
in  the  little  air  sacs  is  seldom  changed,  but  remains 
more  or  less  stagnant,  the  sacs  furnish  excellent  lodg- 
ing places  for  dangerous  bacteria,  and  they  may  even 
be  the  starting  point  for  consumption,  pneumonia,  or 
some  other  lung  disease.  If  people  exercised  the  air 
sacs  more  vigorously,  filling  them  constantly  with  fresh 
air,  the  danger  of  lung  trouble  would  be  decreased. 

How  shall  we  give  our  lungs  the  needed  exercise  ?  By 
drawing  long,  deep  breaths,  filling  the  lungs  as  full  as 
possible,  and  then  blowing  out  the  air  slowly  and  forci- 
bly. If  we  acquire  a  habit  of  frequently  filling  the  lungs 
deeply  with  fresh  out-of-door  air,  we  shall  strengthen 
them,  increase  their  capacity,  and  improve  our  general 
health.  Persons  whose  work  is  such  as  to  produce  vig- 
orous activity  of  the  lungs  do  not  need  such  special 
exercise.  If  one  is  obliged  to  walk  up  a  steep  hill 
daily,  so  that  he  becomes  somewhat  breathless,  the  lungs 


RESPIRATION  113 

receive  all  the  exercise  needed  to  keep  them  properly 
active.  The  active  boy  or  girl  ordinarily  gets  plenty 
of  lung  exercise  in  play.  It  is  important  to  remember, 
however,  that  with  the  quiet  life  which  many  persons 
live,  especially  in  our  cities,  the  lungs  need  special 
exercise  to  make  them  strong  and  to  give  them  the 
amount  of  fresh  air  necessary  for  health. 

WHAT  BREATHING  DOES  FOR  THE  BLOOD 

How  Blood  is  changed  in  the  Lungs.  —  The  blood 
which  enters  the  lungs  to  be  purified  is  very  different 
from  the  blood  which  returns  from  the  lungs  to  the 
heart.  Four  important  changes  occur  in  the  lungs. 

1.  The  blood  takes  up  oxygen  from  the  air.  —  The  red 
corpuscles  have  the  power  of  taking  up  oxygen  from 
the  air.     Each  one  of  the  millions  of  these  corpuscles 
takes  from  the  air  in  the  lungs  as  much  of  the  oxygen 
as   it   can  hold.      As   soon   as   the  oxygen  has  been 
absorbed,  the  corpuscle   becomes  a  brighter  red  than 
before,  and  consequently  the  blood  itself  is  of  a  more 
brilliant  color.     The  blood  that  flows  into  the  lungs  is 
bluish  red ;  the  blood  that  comes  out  is  bright  scarlet. 

2.  The  blood  gives  up  carbon  dioxide  gas.  —  The  car- 
bon dioxide  gas  leaves  the  blood,  enters  the  air  in  the 
lungs,  and  is  then  expelled  in  the  exhalation. 

3.  The   blood   is    cooled.  —  The   blood    is   somewhat 
cooled  while  it  is  flowing  through  the  lungs.     The  air 
which  we  breathe  into  our  lungs  is  usually  cooler  than 
the  body.     In  an  ordinary  schoolroom  it  is  about  70°. 
But  the  same  air  when  expelled  from  the  lungs  is  nearly 


114  PHYSIOLOGY  AND  HYGIENE 

as  warm  as  the  body  (about  98°).  It  has  been  warmed 
in  the  lungs  by  the  blood,  the  blood  itself  being  cooled 
at  the  same  time. 

4.  The  blood  loses  some  of  its  water  in  the  lungs.  —  If 
we  breathe  upon  a  cold  windowpane,  little  drops  of 
water  collect,  making  the  glass  cloudy.  These  drops 
condense  from  the  moisture  we  exhale.  The  air 
breathed  from  the  lungs  is  usually  nearly  saturated 
with  vapor.  When  we  walk  out  of  doors  on  a  cold 
winter's  morning,  we  can  "see  our  breath";  that  is, 
the  water  in  the  breath  condenses  into  a  slight  fog 
as  it  comes  from  the  mouth  or  nostrils.  This  water  all 
comes  from  the  blood.  Thus  the  blood  on  leaving  the 
lungs  contains  less  water  than  when  it  enters. 

How  the  Oxygen  is  Used.  — After  the  blood  has  taken 
the  oxygen  from  the  air  in  the  lungs,  it  goes  directly  to 
the  left  side  of  the  heart.  From  there,  as  we  have 
already  learned,  it  is  sent  to  all  parts  of  the  body 
through  the  arteries,  finally  reaching  the  capillaries. 
The  blood  flows  through  the  capillaries  very  slowly, 
and  here  each  red  corpuscle  lets  go  of  the  oxygen  it 
took  while  in  the  lungs.  The  oxygen  passes  at  once 
from  the  blood  to  the  tissues  of  the  body  around  the 
capillaries.  The  red  corpuscles  are  thus  the  oxygen 
carriers.  They  go  to  the  lungs,  seize  the  oxygen,  and 
then  carry  it  to  every  part  of  the  body  needing  it. 
After  they  have  given  up  the  oxygen  they  become 
bluish  red,  so  that  the  blood  which  leaves  the  capil- 
laries to  go  back  through  the  veins  to  the  heart  is  a  dark 
bluish  red. 


RESPIRATION  115 

We  have  already  seen  that  the  oxygen  is  brought 
into  the  body  to  unite  with  the  food,  just  as  it  unites 
with  the  fuel  in  a  locomotive,  and  that  as  a  result 
there  is  produced  the  waste  gas,  carbon  dioxide. 
While  the  blood  is  passing  through  the  capillaries,  it 
not  only  gives  up  oxygen  to  the  tissues  but  it  takes 
from  them  the  carbon  dioxide  which  has  been  pro- 
duced. Thus  when  it  comes  back  from  the  tissues  to 
the  heart,  the  blood  is  carrying  carbon  dioxide  in  the 
place  of  the  oxygen.  Such  blood  is  called  venous  blood, 
and  is  said  to  be  impure  because  it  contains  waste  prod- 
ucts. When  this  blood  reaches  the  lungs  again  it  gives 
off  the  waste  carbon  dioxide  it  is  carrying  and  gets 
another  load  of  oxygen. 

Respiration  is  then  an  exchange  of  gases  between  the 
body  and  the  air.  The  blood  is  all  the  time  passing 
through  the  lungs  where  it  gives  up  carbon  dioxide, 
water,  and  other  gaseous  waste  products  and  takes 
oxygen.  Going  thence  to  the  various  parts  of  the 
body,  it  supplies  them  with  the  oxygen  and  takes  away 
the  carbon  dioxide.  If  anything  hinders  breathing, 
there  is  trouble,  for  the  same  reason  that  a  fire  will 
not  burn  unless  there  is  a  draft  to  furnish  air  to  the 
burning  coal.  If  breathing  stops  for  more  than  a  few 
minutes  death  follows,  since  the  body  is  then  unable 
to  obtain  oxygen  or  get  rid  of  waste  gas. 

Breathing  and  Exercise. — We  can  readily  under- 
stand why,  if  we  exercise  vigorously,  the  rate  and  the 
depth  of  breathing  will  be  increased.  If  an  engine  is 
to  work  rapidly,  it  must  have  a  good  draft,  and  it  must 


116  PHYSIOLOGY  AND  HYGIENE 

burn  large  quantities  of  coal ;  a  large  amount  of  ashes 
will  be  left,  and  a  great  deal  of  smoke  will  issue  from 
its  chimney.  So  with  our  bodies.  If  we  are  to  work 
our  muscles  vigorously,  we  must  have  a  large  supply 
of  oxygen  to  oxidize  the  necessary  food,  and  an  in- 
creased amount  of  waste  will  be  produced.  The  blood 
must  consequently  flow  faster  than  usual,  both  to 
furnish  the  oxygen  and  to  carry  off  the  waste.  To 
accomplish  this  the  heart  begins  to  beat  faster  so  as  to 
increase  the  speed  of  the  blood,  and  at  the  same  time 
our  breathing  becomes  more  rapid,  so  that  the  rapidly 
flowing  blood  may  be  supplied  with  oxygen,  and  all 
the  waste  may  be  carried  away. 

VENTILATION 

Need  of  Ventilation.  —  It  is  evident  that  we  need  a 
great  deal  of  pure  air.  The  rooms  in  which  we  live 
should  be  well  ventilated.  There  are  two  purposes 
in  ventilation :  1.  To  furnish  us  with  a  sufficient  supply 
of  oxygen;  2.  To  provide  air  that  can  carry  off  dust, 
noxious  gases,  and  moisture. 

Anything  which  uses  up  the  oxygen  in  a  room, 
or  which  allows  too  large  an  amount  of  breathed  air 
to  accumulate,  renders  the  air  unwholesome.  If  a 
great  many  people  are  breathing  the  air  in  a  room, 
or  if  gas  or  oil  stoves  or  lamps  are  using  up  the  oxygen 
and  giving  out  carbon  dioxide,  the  air,  unless  changed, 
becomes  oppressive  and  poisonous.  In  such  cases  it  is 
especially  necessary  to  attend  well  to  the  matter  of 
ventilation. 


RESPIRATION  117 

Evils  of  Indoor  Life.  —  People  who  live  in  warm 
climates  spend  much  of  their  time  out  of  doors.  We 
in  the  colder  climates  have  formed  the  habit  of  living 
in  close  rooms,  where  we  remain  for  hours  at  a  time. 
In  the  close  rooms  we  are  often  forced  to  breathe  over 
and  over  the  air  which  has  already  been  breathed  by 
ourselves  or  other  people,  and  this  is  most  unwhole- 
some. The  habitual  breathing  of  impure  air  is  partly 
the  cause  of  some  of  the  lung  diseases,  as  pneumonia 
and  consumption.  This  does  not  mean  that  people 
living  out  of  doors  never  have  lung  troubles ;  but  such 
diseases  are  most  common  among  those  who  live  in 
close  rooms.  City  workmen,  though  better  fed  than 
country  workmen,  are  usually  less  healthy.  If  we 
could  be  in  the  open  air  most  of  the  time,  we  should 
avoid  many  of  these  difficulties;  but  since  in  cold 
climates  this  is  not  pleasant  in  winter,  we  must  at  least 
keep  our  rooms  supplied  with  plenty  of  fresh  air. 

The  Need  of  Fresh  Air.  —  Many  people  arrange  their 
living  rooms  with  a  wholly  mistaken  idea  of  what  is 
healthful.  They  seem  actually  afraid  of  fresh  air.  So 
careful  are  they  to  prevent  drafts  that  they  exclude 
fresh  air.  They  think  that  they  take  cold  because  the 
rooms  are  not  warm  enough,  or  because  of  changes  in 
temperature,  so  they  keep  the  air  as  uniformly  warm 
as  possible.  Probably  more  colds  are  due  to  over- 
heated or  impure  air  than  to  drafts  or  cold  air.  We 
take  cold  from  drafts  frequently  because  we  accustom 
ourselves  to  living  in  warm  rooms.  A  temperature  of 
from  65°  to  70°,  depending  upon  how  actively  we  are 


118  PHYSIOLOGY  AND  HYGIENE 

employed  at  the  time,  is  the  proper  temperature  for 
living  rooms  in  cold  weather. 

A  very  large  class  of  people  consider  night  air 
especially  dangerous,  and  for  this  reason  they  sleep  in 
rooms  closed  up  tightly,  to  prevent  fresh  air  from 
entering.  Night  air  is  no  more  injurious  than  day 
air,  except  that  it  is  likely  to  bring  mosquitoes,  which 
should  be  kept  out  of  the  sleeping  room ;  and  there 
is  no  time  when  a  person  should  be  more  partic- 
ular that  the  air  is  pure  than  when  he  sleeps.  The 
attempt  to  shut  out  night  air  from  sleeping  rooms  is  a 
grave  mistake,  and  this  is  true  both  in  winter  and  in 
summer.  Fresh  air  is  one  of  nature's  best  remedies 
for  many  diseases.  If  we  determine  to  make  it  a 
point  through  life  to  breathe  plenty  of  wholesome,  fresh 
air,  we  have  laid  a  firm  foundation  for  vigorous  health. 

How  Rooms  are  Ventilated.  —  More  or  less  fresh  air 
gets  into  the  rooms  of  an  ordinary  dwelling  house,  no 
matter  how  tightly  they  may  be  closed.  If  a  stove  is 
used  in  a  room,  the  fire  causes  a  continuous  draft  up 
the  chimney ;  this  draft  always  removes  air  from  the 
room,  and  fresh  air  is  drawn  in  from  outside  to  take 
its  place.  The  air  comes  in  through  the  cracks  about 
the  doors  and  windows,  through  the  keyholes,  and  more 
or  less  through  cracks  in  the  floors.  The  direction  of 
the  currents  of  air  may  be  seen  from  Figure  40.  When 
there  are  only  one  or  two  persons  in  a  room,  and  the 
doors  are  opened  frequently,  sufficient  fresh  air  is  usually 
supplied  from  these  sources.  At  night  such  ventilation 
is  not  enough.  Unless  the  wind  blows  very  hard,  some 


RESPIRATION 


119 


arrangements  should  be  made  for  constant  change  of  air, 
such  as  opening  a  window  at  the  top  in  such  a  way  that 
those  sleeping  in  the  room  will  not  feel  a  direct  draft. 
An  open  fireplace,  even  if  there  be  no  fire  in  it,  is  an 
excellent  means  of  ventilation,  as  shown  in  Figure  40. 

In  houses  heated  by  means  of  hot-air  furnaces  special 
devices  are  usually  adopted  for  supplying  fresh   air. 


FIG.  40.  —  VENTILATION. 
Showing  the  means  by  which  air  enters  and  leaves  an  ordinary  room. 

The  furnace  is  connected  with  what  is  called  the  cold 
box,  which  is  open  to  the  outdoor  air.  The  air  enters 
this  box,  passes  into  the  furnace,  is  there  heated,  and 
then  rises  through  the  flues  into  the  different  rooms. 
All  the  while  air  is  passing  out  of  the  rooms  through 
cracks  in  the  doors  and  windows,  or  rising  through 
halls  or  ventilating  flues  in  chimneys,  which  are  usually 
left  open  in  such  houses. 

When  houses  are  heated  by  steam  radiators  it  is  not 
so  easy  to  keep  the  air  pure ;  for  although  currents  of 


120  PHYSIOLOGY  AND   HYGIENE 

air  move  up  and  down  in  the  room  they  do  not  readily 
pass  out,  and  we  must  depend  for  fresh  air  upon  flues 
and  open  fireplaces.  The  difficulty  in  keeping  a  free 
circulation  of  air  is  partly  the  reason  why  a  room 
heated  by  steam  is  apt  to  be  "stuffy."  In  such  a  room 
there  should  always  be  some  special  arrangement  for 
the  outlet  and  inlet  of  air.  Sufficient  movement  of  the 
air  may  be  obtained  by  means  of  open  fireplaces,  flues 
in  the  chimneys,  ventilators  around  the  windows,  or 
windows  slightly  open  at  top  and  bottom.  When  a 
house  with  many  doors  and  windows  has  many  of  its 
rooms  opening  into  each  other,  ventilating  flues  are  not 
especially  necessary. 

When  a  room  —  such  as  a  schoolroom  or  a  public 
hall  —  holds  a  number  of  persons,  special  means  should 
be  adopted  for  replacing  impure  air.  Such  rooms  are 
usually  provided  with  special  ventilating  apparatus. 

It  is  worth  while  to  remember,  in  any  case,  that  cold, 
fresh  air,  from  whatever  source  it  may  come,  is  less 
injurious  than  breathing  repeatedly  the  air  of  a  close, 
ill-ventilated  room.  There  is  one  simple  test  of  the 
ventilation  of  a  room:  Does  the  air  seem  fresh  and 
sweet  as  you  come  from  the  pure  outside  air  ? 

HOW  TO  RESTORE  RESPIRATION 

Occasionally  some  accident  stops  a  person's  breath- 
ing and  tends  to  produce  suffocation.  For  example, 
when  a  person  is  submerged  in  water  he  can  no 
longer  take  air  into  his  lungs.  If,  however,  the 
drowning  person  can  be  removed  from  the  water 


RESPIRATION 


121 


while  the  heart  still  beats,  and  breathing  can  be  started 
again,  his  life  can  usually  be  saved.  After  being  taken 
from  the  water,  the  patient  should  be  placed  so  that  the 
head  is  lower  than  the  shoulders,  and  turned  face 
downward,  to  allow  the  water  to  run  out  of  the  mouth 
and  throat. 

The  process  of  arti- 
ficial breathing  should 
then  be  started.  The 
patient  should  be  placed 
on  his  back,  with  the 
head  on  a  level  with 
the  body.  The  arms 
should  be  first  pressed 
against  the  sides  of  the 
body,  and  then  raised 
outward  and  upward 
until  they  meet  above 
the  patient's  head. 
Lifting  the  arms  in 
this  way  raises  the  FIG.  41.  —  THE  METHOD  OF  MOVING 

.          ,  ,  ,        .,  ,  ,  THE   ARMS    TO   PRODUCE  ARTIFICIAL 

shoulders  and  ribs ;  the       BREATHING. 
size     of     the    chest    is 

thus  increased,  and  air  is  drawn  into  the  lungs.  It 
is  important  to  know  that  the  air  actually  passes  into 
the  lungs.  To  be  sure  of  this,  the  tongue  must  be 
drawn  forward  so  as  to  open  the  throat  and  permit  the 
air  to  pass.  After  the  arms  have  been  lifted,  they 
should  be  lowered  again,  while  a  second  person,  if  pos- 
sible, presses  the  abdomen  and  sides  of  the  body.  The 


122  PHYSIOLOGY   AND  HYGIENE 

lowering  of  the  arms  and  the  pressure  on  the  abdomen 
tend  to  force  the  air  out  by  compressing  the  chest. 
The  raising  and  lowering  of  the  arms  in  this  manner 
should  be  continued  regularly  from  ten  to  twelve  times 
a  minute,  and  should  be  kept  up  until  natural  breathing 
starts.  Although  this  work  is  hard,  it  should  be  kept 
up  for  at  least  two  hours  if  normal  breathing  is  not 
resumed  earlier. 

A  feather  or  other  light  object  placed  in  front  of  the 
mouth  will  show  when  natural  breathing  begins.  If 
there  is  any  motion  of  the  feather  to  indicate  natural 
breathing,  the  movements  of  the  arms  may  be  stopped. 
The  person  should  then  be  wrapped  in  warm  clothing 
or  in  blankets,  and  nature  will  complete  the  restoration, 
although  it  will  be  an  aid  to  have  the  extremities  of 
the  patient  rubbed  during  the  whole  process.  This 
method  of  restoration  should  be  employed  if  a  person 
becomes  nearly  suffocated  from  any  cause.  Persons 
have  sometimes  been  in  the  water  a  quarter  of  an  hour 
or  even  longer,  and  have  still  been  brought  back  to 
consciousness. 

QUESTIONS 

1.  What  gas  is  necessary  for  oxidation?    What  products  re- 
sult from  oxidation  ? 

2.  Why  should  we  keep  our  mouths  shut  except  when  talking 
or  eating  ? 

3.  Where  is  the  windpipe  ? 

4.  Of  what  use  is  the  larynx  ? 

5.  Where  are  the  lungs  situated  ? 

6.  How  does  the  blood  get  oxygen  from  the  lungs? 

7.  How  is  air  drawn  into  the  lungs  ? 


RESPIRATION  123 

8.  Could  a  person  breathe  if  there  were  a  hole  through  the 
chest?    Why? 

9.  What  form  the  walls  of  the  chest? 

10.  How  is  the  chest  cavity  made  larger  or  smaller? 

11.  If  air  is  taken  into  the  chest  only,  why  does  the  abdomen 
swell  out  with  each  inspiration  ? 

12.  How  much  of  the  air  in  the  lungs  is  changed  at  a  single 
breath  ? 

13.  How  can  we  exercise  the  lungs  ? 

14.  What  four  things  happen  to  the  blood  in  the  lungs  ? 

15.  What  does  the  blood  do  with  the  oxygen  it  takes  from  the 
lungs  ? 

16.  If  one  should  have  too  few  red  corpuscles  in  his  blood,  what 
would  be  the  result  ? 

17.  What  is  respiration  ? 

18.  When    you  are  running,  can    you    breathe   more   easily 
through  your  mouth  ?     If  you  do,  can  you  run  farther  ? 

19.  Why  does  a  schoolroom  need  better  ventilation  than  a  com- 
mon dwelling  room  ? 

20.  What  are  the  purposes  in  ventilation  ? 

21.  What  are  the  evils  of  indoor  life? 

22.  How  should  rooms  heated  by  stoves  and  furnaces  be  venti- 
lated? 

23.  What  may  be  done  to  ventilate  houses  heated  by  steam? 

24.  How  may  natural  breathing  be  restored  when  a  person  has 
been  almost  drowned  ? 


CHAPTER  VI 
THE   FRAMEWORK   AND  MOTION   OF   THE   BODY 

THE  stomach  digests  food,  the  heart  and  the  blood 
vessels  are  in  constant  action,  the  lungs  never  cease  to 
expand  and  contract  as  long  as  we  live.  Those  Qrgans, 
then,  all  have  a  part  in  aiding  us  to  accomplish  the  work 
that  is  given  us  to  do.  But  with  stomach,  heart,  and 
lungs  alone  we  could  neither  step,  nor  speak,  nor  move 
in  any  way.  We  must  have  in  addition  muscles  and 
bones.  Of  these  our  bodies  are  largely  made,  and  it 
is  to  repair  and  renew  these,  as  well  as  to  render  them 
of  practical  use,  that  we  possess  the  organs  about 
which  we  have  already  studied. 

THE  SKELETON 

Most  of  the  parts  of  our  bodies  are  soft,  and  if  there 
were  not  a  hard  framework  to  support  them,  we  should 
be  nearly  as  flexible  as  jellyfish.  But  inside  the  pli- 
able flesh  we  have  solid  bones,  which  serve,  like  the 
beams  of  a  house,  as  a  support  for  the  softer  parts. 
This  framework  of  bones  is  called  the  skeleton.  A 
grown  person  has  in  his  body  two  hundred  different 
bones.  A  child  has  even  more,  but  several  of  the 
bones  grow  together  later,  making  just  two  hundred. 

124     • 


FRAMEWORK   AND  MOTION  OF   THE  BODY      125 


Tana/ Bones 
Jleto  Tonal* 


FIG.  42.  —  THE  HUMAN  SKELETON. 


126 


PHYSIOLOGY  AND  HYGIENE 


The  bones  are  of  different  shapes  and  sizes.  Figure 
42  shows  the  framework  of  the  body,  indicating  the 
position  and  shape  of  the  various  bones.  As  will  be 
seen  from  the  figure,  there  is  in  the  middle  of  the  back 
a  strong  support,  called  the  backbone.  It  is  not  one 
single  piece,  however,  but  a  series  of  small  bones 

fitting     snugly     to- 


Spinol  Cord 


gether    and    capable 


of  being  moved.  If 
the  back  contained 
only  one  bone,  it 
would  be  stiff  arid 
easily  broken,  but 
this  series  of  small 
bones  enables  us  to 
bend  the  back  with- 
out danger  of  break- 
ing it.  Each  of  the 
smaller  bones  of  the 
back  is  called  a  verte- 
bra. Figure  43  shows 

two  vertebrae.  Many  other  animals  have  backbones 
made  up  of  vertebrae.  These  include  fishes,  reptiles, 
birds,  and  the  four-footed  animals  with  which  we  are 
familiar.  All  such  animals  are  called  vertebrates. 

Figure  42  shows  a  large,  rounded  box  just  above  the 
backbone.  This  is  the  skull,  which  forms  the  head.  A 
side  view  is  given  in  Figure  44.  The  skull  is  one  of 
the  most  important  parts  of  the  body,  because  of  the 
organs  it  contains.  In  it  are  the  brain,  the  eyes,  the 
ears,  and  the  organs  of  taste  and  smell. 


^f -Spinal  Cord 

FIG.  43.  —  Two  VERTEBRA  IN  POSITION. 

Showing  the  spinal  cord  passing 

through  them. 


FRAMEWORK  AND  MOTION  OF  THE  BODY      127 


The  chest,  as  we  already  know,  contains  the  heart 
and  the  lungs.  It  is  nearly  surrounded  by  curved 
bones  called  the  ribs.  These  extend  from  the  back- 
bone around  to  the  front.  The  heart  and  the  lungs 


Cranium 


Facial 
forte* 


Occipital 


ManMe 
FIG.  44.  — THE  HUMAN  SKULL. 

are  surrounded  and  thoroughly  protected  by  these  ribs 
and  the  breastbone,  or  sternum. 

Each  of  the  arms  and  legs  is  made  up  of  several  bones. 
In  Figure  42  these  bones  are  named.  The  bones  of  the 
arms  and  legs  are  the  longest  in  the  body.  Since  they 
are  the  ones  that  must  bear  the  heaviest  strains,  they 
are  also  the  strongest  bones  of  the  body. 


128 


PHYSIOLOGY    AND  HYGIENE 


Ham* 


THE  BONES 

Structure  of  Bone.  —  The  different  bones  are  of  various 
shapes,  but  they  are  all  so  made  as  to  have  the  greatest 
strength  and  at  the  same  time  to  be  comparatively  light. 
For  example,  the  long  bones  of  the 
leg  and  the  arm,  which  must  bear  the 
greatest  strains,  are  hollow.  Figure 
45  represents  the  longest  bone  of  the 
leg,  cut  open  lengthwise.  At  the 
ends  the  bones  are  spongy,  but 
throughout  the  length  of  the  shaft 
they  are  hollow.  This  shape  gives 
the  greatest  possible  amount  of 
strength  to  the  bone  for  a  given 
weight  of  bony  substance.  Although 
not  all  the  bones  are  hollow  like  those 
of  the  leg,  still  all  are  so  built  as  to 
make  the  skeleton  strong  and  light. 
This  allows  greater  ease  of  motion 
than  would  be  possible  if  the  bones 
were  heavier,  and  yet  renders  them 
sufficiently  strong  for  the  work  they 
J^.  do. 

7  ™  i 

Bone  Materials.  —  Bones  are  made 

of  two  different  materials,  one  of 
which  is  called  mineral  matter,  the  other  animal  mat- 
ter. The  mineral  matter  is  hard  and  brittle,  and 
gives  stiffness  to  the  bone.  If  we  put  a  bone  upon 
a,  hot  coal  fire,  and  allow  it  to  stay  there  for  half 


FIG.  45.  —  A  SECTION 
OF  THE  FEMUR. 

Showing  the  spongy 
ends  and  hollow 
center. 


FRAMEWORK   AND  MOTION  OF  THE  BODY      129 

an  hour,  it  will  be  very  much  changed.  Though  the 
shape  will  be  the  same,  the  heat  has  made  the  bone 
light  and  very  brittle,  so  that  it  can  be  crumbled  to 
a  powder  in  the  fingers.  The  hot  fire  has  burned  the 
animal  matter  out  of  the  bone,  leaving  only  the  mineral 
matter,  which  is  something  like  stone,  and  cannot  be 
burned.  On  the  other  hand,  if  we  put  a  small  bone, 
such  as  a  chicken  bone,  into  a  dish  of  dilute  nitric  acid 
and  allow  it  to  remain  there  for  a  day  or  two,  the  acid 
will  take  out  all  the  mineral  matter.  Upon  removing 
the  bone  from  the  acid,  we  shall  find  it  unchanged  in 
shape  and  size,  but  soft  and  flexible,  so  that  we  can 
bend  it,  and  perhaps  even  tie  it  into  a  knot.  What 
is  left  is  animal  matter  only. 

The  mineral  and  the  animal  matter  are  united  in  bone 
so  as  to  form  one  substance.  The  animal  matter  gives 
strength,  while  the  mineral  matter  gives  hardness. 

Bones  of  Children.  —  Occasionally  a  child  may  fall 
down  a  flight  of  stairs  with  no  ill  effects  save  a  few 
black-and-blue  spots,  while  the  same  fall  would  be 
likely  to  injure  a  grown  person  seriously.  The  reason 
is  that  there  is  proportionately  more  animal  matter  in 
the  bones  of  children  than  in  those  of  adults,  and  the 
bones  of  children  are  therefore  more  easily  bent  and 
are  not  so  brittle.  In  very  early  childhood  the  bones 
are  made  entirely  of  animal  matter,  and  are  conse- 
quently soft  and  flexible  like  the  bone  which  has  been 
soaked  in  acid.  As  the  child  grows,  more  and  more 
of  mineral  matter  is  deposited  in  the  bones,  until  finally 
they  become  hard  and  stiff. 


130  PHYSIOLOGY  AND  HYGIENE 

During  the  first  few  years  of  a  child's  life  the  bones 
are  so  flexible  that  they  can  be  bent  out  of  shape  more 
easily  than  in  later  life.  For  this  reason  special  pains 
should  be  taken  to  teach  children  to  hold  the  body 
erect.  A  good  carriage  in  walking  can  be  learned  by 
every  one,  but  most  easily  by  children.  The  chest 
should  be  held  up  properly,  and  the  chin  kept  in,  not 
thrust  forward.  If  the  chest  is  kept  up  and  the 
shoulders  are  thrown  back,  the  body  will  take  the  best 
position  for  walking  and  standing.  When  sitting  we 
should  take  care  to  sit  with  head  erect,  and  with  the 
back  against  the  back  of  the  chair  or  bench. 

Misshapen  Bones.  —  If  the  bones  of  a  child  are  con- 
stantly bent  in  one  direction,  they  will  be  deformed. 
Although  it  is  easy  for  a  child  to  stand  and  sit  erect,  it 
is  equally  easy  to  become  "round-shouldered."  After 
the  bones  have  hardened  it  is  as  difficult  to  change  the 
habits  as  it  was  easy  to  form  them,  and  later  in  life  it 
may  be  impossible.  Any  kind  of  dress  that  causes 
strong  and  long- continued  pressure  on  the  bones  is 
likely  to  cause  a  misshapen  body. 

Wearing  tight  shoes  will  deform  the  bones  of  the 
feet.  Figure  46  indicates  the  shape  of  the  toes  of  a 


FIG.  46.  —  THE  CRAMPED  FOOT.     FIG.  47.  —  THE  UNCRAMPED  FOOT. 

person  who  wears  tight  shoes.     Figure  47  indicates  the 
shape  the  foot  takes  when  it  is  not  cramped.    Wrongly 


FRAMEWORK  AND  MOTION  OF  THE  BODY      131 

shaped  and  tight  shoes  cause  much  discomfort  and 
render  walking  difficult,  besides  putting  the  feet  in 
such  a  condition  that  the  person  is  likely  to  suffer  from 
the  effects  all  through  life.  Deformed  feet  may  be 


FIG.  48.  —  AN  IMPROPERLY       FIG.  49.  —  A  PROPERLY  SHAPED 
SHAPED  SHOE.  SHOE. 

produced  by  shoes  with  narrow  toes  or  with  heels 
so  placed  as  to  throw  the  weight  of  the  body  upon  the 
toes,  as  shown  in  Figure  48.  A  properly  shaped  shoe 
is  shown  in  Figure  49. 

A  habit  even  worse  than  pinching  the  feet  is  that 
of  wearing  tight  bands  round  the  waist,  or  tight  cor- 
sets. This  gives  rise  to  serious  deformities,  affecting 
not  only  the  bones  but  also  the  important  vital  organs 
of  the  abdomen  which  are  pressed  out  of  proper  posi- 
tion. The  leather  belts  sometimes  worn  by  boys  and 
young  men  with  outing  costumes,  if  drawn  tight 
around  the  waist,  instead  of  being  placed  over  the  hips, 
are  almost  equally  bad.  Good  health  requires  that 
the  body  be  allowed  to  grow  as  nature  intended, 
unconfmed  by  tight  clothing. 


132  PHYSIOLOGY  AND  HYGIENE 

Habits  of  stooping  over  one's  work,  of  leaning  against 
a  support  instead  of  standing  erect,  of  standing  con- 
stantly upon  one  foot  without  bearing  sufficient  weight 
upon  the  other,  of  walking  or  sitting  with  stooped 
shoulders  and  with  the  head  thrown  forward,  or  of 
wearing  clothing  which  binds  the  body  —  any  of  these 
habits  will  destroy  the  beauty  of  the  form  and  impair 
bodily  strength.  Among  the  prime  necessities  for 
attractiveness  in  appearance  is  an  erect  manner  of 
walking  and  sitting,  without  slouching.  The  cadets  in 
the  military  schools  owe  much  of  their  fine  appearance 
to  constant  drills,  which  exercise  all  the  muscles,  and 
which  keep  the  body  erect. 

Repair  of  Broken  Bones.  —  As  many  a  boy  knows 
from  personal  experience,  bones  will  occasionally  get 
broken  in  spite  of  the  fact  that  they  are  tough  and 
strong.  Very  fortunately,  unlike  broken  teeth,  bones 
when  broken  can  be  mended.  Each  bone  is  supplied 
with  one  or  more  tiny  blood  vessels,  which  furnish 
blood  for  its  nourishment.  The  animal  matter  in  the 
bone  is  alive,  and  so  is  able  to  grow. 

If,  after  a  bone  is  broken,  the  two  ends  are  brought 
nicely  together,  this  living  part  of  the  bone  begins  to 
make  new  bony  material,  which  grows  between  the 
ends,  finally  uniting  them  again  as  strongly  as  ever. 
The  bone  must  be  kept  still  until  it  is  firmly  knit,  for 
any  motion  would  pull  the  ends  apart.  For  this  rea- 
son the  physician  binds  the  broken  bone  tightly  in 
splints.  The  setting  of  a  broken  lone  consists  simply 
in  bringing  the  broken  ends  together  and  binding  them 
in  the  proper  position. 


FRAMEWORK  AND  MOTION  OF  THE  BODY      133 

Since  there  is  more  animal  matter  in  the  bones  of  a/ 
child  than  in  those  of  a  grown  person,  broken  bones) 
are  more  easily  mended  in  childhood.  In  old  age  the 
amount  of  animal  matter  is  less,  so  that  the  bones  are 
more  brittle  and  more  easily  broken.  They  are  also 
less  easily  repaired. 

CARTILAGE 

The  framework  of  the  body  is  not  wholly  bone.  A 
part  of  it  is  made  of  a  substance  called  cartilage.  This 
is  so  soft  that  it  can  be  cut  with  a  knife.  It  is  so 
flexible  that  it  can  be  bent  easily,  but  at  the  same  time 
it  is  very  tough.  It  is  found  in  several  places  in  the 
body  where  there  is  need  of  greater  flexibility  than 
bone  would  give.  For  example,  the  ribs  are  united 
with  the  breastbone  at  the  front  of  the  chest  (see  Fig. 
42)  by  little  pieces  of  cartilage.  This  makes  them 
slightly  movable  and  not  Cartilage 

easily  broken.  Little 
cushions  of  cartilage  are 
also  found  between  the 
vertebrae  of  the  backbone, 
as  indicated  in  Figure  50. 
Here  they  relieve  the  jar 
which  would  result  from 
a  jump,  if  the  bones  actu-  FIG.  50.  -  Two  VERTEBRA. 

ally  touched  each  other.  ShowinS  the  cartila^  cushion  that 

J  .  separates  them. 

There  are  pieces  of  carti- 
lage  around  the  larynx,  and  the   outer   ear  is  made 
entirely   of  cartilage   covered   with    skin.      Cartilage 


134  PHYSIOLOGY  AND  HYGIENE 

is  not  easily  broken,  but  if  once  severed,  it  does  not 
mend  so  easily  as  bone.. 

JOINTS 

When  we  consider  that  the  framework  of  our 
bodies  is  made  of  two  hundred  separate  pieces,  we 
wonder  how  they  can  ever  be  united  in  a  firm  struc- 
ture. They  are  fastened  as  firmly  as  the  parts  of  a 
house  are  nailed  together.  In  some  places,  as  in  the 
skull,  they  are  so  united  that  they  cannot  be  moved. 
In  other  places,  as  at  the  elbow  and  in  the  fingers,  they 
can  be  turned  about  freely.  Whenever  two  bones  come 
together  they  form  a  joint.  If  it  were  not  for  our 
joints  we  could  not  move  ;  and  when  an  accident  injures 
a  joint,  we  become  stiff  and  lame.  There  are  two 
principal  kinds  of  joints  in  the  body,  the  hinge  joint 
and  the  ball-and-socket  joint.  Let  us  see  what  each  is 
like. 

A  Hinge  Joint.  —  The  bones  forming  a  hinge  joint  can 
be  moved  back  and  forth  in  one  direction  only,  like  a 
door  on  its  hinges.  The  joints  at  the  knee  and  the 
elbow  are  of  this  character,  as  is  also  each  joint  of  the 
finger.  If  we  try  to  move  the  finger  or  the  elbow,  we 
find  that  it  will  move  in  one  direction  only.  The  hinge 
joints  are  all  so  much  alike  that  we  need  to  study 
only  one  in  detail.  Let  us  take  the  knee  joint  as  an 
illustration. 

Two  bones  come  together  at  the  knee  to  form  the 
joint, — the  thigh  bone,  or  femur,  and  the  shin  bone,  or 
tibia,  as  shown  in  Figure  51.  The  ends  of  these  bones 


FRAMEWORK  AND  MOTION  OF  THE  BODY      135 

are  large  and  rounded,  and  the  two  fit  together  so 
as  to  be  very  easily  moved.  As  can  be  seen  from 
Figure  51,  these  bones  are  so  shaped  that  they  can  be 
moved  back  and  forth,  but  not  side  wise.  The  ends 


Fibuk 

FIG.  61.  —  THE  BONES  FORMING  THE  KNEE  JOINT. 

of  the  bones,  which  are  rounded  and  smooth  in  them- 
selves, are  made  still  smoother  by  being  covered  with 
a  laryer  of  soft  cartilage. 

^To  keep  the  parts  of  a  bicycle  in  smooth  running 
order  we  oil  them.  The  various  joints  of  the  body 
are  provided  with  a  liquid  that  takes  the  place  of  oil 
in  the  wheel.  This  is  the  way  it  is  arranged  :  the 
bones  of  the  joint  are  partly  surrounded  by  a  thin 
membrane  or  tissue,  which  supplies  a  liquid  to  the  joint 
between  the  two  bones.  The  liquid  moistens  the  ends 
of  the  bones,  thus  preventing  friction.  If  it  were  not 
for  this  liquid  the  bones  would  rub  against  each  other, 
and  it  would  be  impossible  to  use  the  joint.  The 


136 


PHYSIOLOGY  AND  HYGIENE 


shapes  of  the  bones  themselves  and  their  smooth  ends, 
together  with  the  liquid,  allow  very  free  motion. 

How  the  Bones  are  held  together.  —  No  matter  how 
nicely  two  bones  might  be  fitted  together,  if  they  were 
not  well  fastened  in  some  way  the  slightest  twist  would 
put  them  "out  of  joint."  As  it  is,  a  bone  occasionally 

.Anterior 
L/yame/tt 


Me/fa 


Capsular  \ 
Ligament,* 

Posterior 
Ligament\ 

FIG.  62.  —  THE  KNEE  JOINT. 
Showing  the  ligaments  connecting  the  bones. 

slips  out  of  place,  but  only  when  there  is  a  severe 
strain  of  the  joint.  To  avoid  such  danger  the  ends  of 
the  bones  are  fastened  together  by  two  kinds  of  con- 
necting bands  which  extend  from  one  bone  to  the  other. 
These  are  ligaments  and  muscles. 

The  ligaments  are  made  of  a  white,  tough,  flexible  sub- 
stance. Several  ligaments  may  be  seen  in  Figures  51 
and  52.  They  pass  from  one  bone  to  the  other  across 
the  joint.  Some  of  them  are  placed  in  front,  some  at 
the  sides,  and  some  at  the  back.  The  ligaments  are, 
however,  rather  loose,  so  that  while  the  bones  cannot 
slip  out  of  place,  they  might,  if  they  were  held  in  no 
other  way,  move  too  freely. 


FRAMEWORK   AND  MOTION   OF  THE  BODY      137 

In  addition  to  the  ligaments,  therefore,  the  bones 
are  held  in  position  by  means  of  certain  muscles.  The 
motion  of  the  bones  at  the  knee  joint  is  produced  by  the 
/  muscles,  all  of  which  lie  above  the  knee.  From  the 
ends  of  the  muscles,  long,  slender  cords  or  tendons  pass 
down  over  the  knee  joint  and  are  attached  to  the  bones 
below  the  knee.  These  muscles  are  elastic  and,  being 
slightly  stretched,  they  help  to  hold  the  bones  in  close 
contact.  Outside  of  the  muscles  is  the  skin,  which 
covers  the  bones,  tendons,  ligaments,  and  muscles,  form- 
ing a  protection  for  them  all. 

We  move  our  joints  so  unconsciously,  as  we  take  a 
step  forward  or  sit  down  in  a  chair,  that  we  hardly 
realize  how  complicated  they  really  are.  But  when  we 
consider  that  so  complicated  and  well-fitted  an  arrange- 
ment is  provided  simply  to  enable  us  to  move  a  knee, 
we  cannot  fail  to  hold  these  bodies  of  ours  in  great 
respect.  A  single  hinge  joint  means  that  we  have 
two  smooth  bones  rounded  just  so  as  to  fit  into  each 
other,  strong  ligaments  to  bind  them  together,  muscles 
and  tendons  to  assist  in  movement,  and  a  protecting 
skin  surrounding  all. 

Other  Hinge  Joints. — The  other  hinge  joints  of  the 
body  are  like  the  knee  joint.  In  all  cases  the  bones 
are  rounded  and  are  moistened  with  the  liquid  to  pre- 
vent friction.  All  are  held  together  by  muscles  and 
ligaments,  and  all  are  so  arranged  that  they  can  be 
moved  in  only  one  direction.  The  joints  at  the  elbows, 
at  the  wrist  and  ankle,  and  in  the  fingers  and  leg  are 
all  hinge  joints. 


138 


PHYSIOLOGY  AND   HYGIENE 


A  Ball-and-Socket  Joint.  —  To  show  the  arrangement 
of  a  ball-and-socket  joint  we  will  study  the  shoulder  joint. 
In  general  such  a  joint  allows  the  bones  to  move  in  every 
direction.  We  can  lift  the  arm  above  the  head,  to  the 
front,  to  the  side,  turn  it  around,  and  bend  it  backward 
as  far  as  the  hinge  joint  at  the  elbow  will  allow.  The 
two  bones  which  form  the  shoulder  joint  are  the 

shoulder  blade,  or  scapula, 
and  the  upper  arm  bone, 
or  humerus.  The  shapes 
of  these  bones  may  be  seen 
from  Figure  53. 

As  is  evident  from  the 
illustration,  the  shoulder 
blade  has  a  somewhat 
rounded  hollow.  The  up- 
per end  of  the  arm  bone 
is  rounded  like  a  ball 
and  fits  into  this  socket  or 
hollow.  Since  the  end  of 
the  arm  bone  is  a  ball,  and  the  socket  in  the  shoulder 
blade  is  a  hollow  cavity,  the  arm  can  be  moved  in  all 
directions.  It  is  this  shape  of  the  bones  that  gives  us 
our  great  freedom  in  lifting  the  arms.  The  ends  of  the 
bones  are  not  only  rounded,  but  they  are  made  particu- 
larly smooth  by  being  covered  with  cartilage,  and  they 
are  also  moistened  with  liquid  like  that  in  the  hinge 
joint. 

The  bones  are  bound  together  at  the  shoulder  by  just 
such  strong  bands  as  we  saw  at  the  knee.  There  is, 


FIG.  53.  —  THE  BONES  OF  THE 
SHOULDER  JOINT. 


FRAMEWORK  AND  MOTION  OF   THE  BODY      139 


however,  as  Figure  54  shows,  only  one  important  liga- 

ment.   It  is  a  loose,  leathery  sac  fastened  to  the  shoulder 

blade.  From  the  shoulder 

blade  it  passes  over  the 

joint  on  all  sides,  and  is 

attached  to  the  upper  end 

of  the  arm  bone,  so  as  to 

cover    the     joint     com- 

•  \  i  -, 

pletely,  and  hold  the  end 

of   the  arm   bone  in  the 
socket.     If  this  ligament 

should  be   Cut,  the  bones 


U(J 


FIG.  54.  —  THE  SHOULDER  JOINT. 

Showing  iigaments, 


could  be  taken  apart  very 
easily. 

The  strength  of  the  shoulder  joint  is  due  very  largely 
to  the  fact  that  it  is  surrounded  by  strong  muscles. 
These  muscles  cover  the  joint  on  all  sides,  giving  it 
great  strength  and  firmness.  The  muscles  in  the 
shoulder  have  tendons  which  pass  down  over  the  joint 
and  are  fastened  to  the  arm  bone,  thus  holding  it 
firmly  in  position. 

Other  Ball-and-Socket  Joints.  —  The  only  large  ball- 
and-socket  joints  in  the  body,  besides  those  at  the 
shoulders,  are  at  the  hips.  The  hip  joint  allows  the  leg 
to  be  moved  in  various  directions,  but  the  movement  is 
not  quite  so  free  as  that  at  the  shoulder. 

Injuries  to  Joints.  —  There  are  two  kinds  of  injuries 
to  joints  which  are  common.  They  are  dislocations  and 
sprains. 

A  bone  pulled  out  of  its  place  in  the  socket  pro- 


140  PHYSIOLOGY  AND  HYGIENE 

duces  a  dislocation.  If,  for  example,  a  fall  or  a  wrench 
should  pull  the  end  of  the  arm  bone  from  the  hollow 
in  the  shoulder  blade  into  which  it  fits,  we  say  the 
shoulder  is  dislocated.  When  a  bone  is  thus  wrenched 
from  its  proper  position  it  cannot  be  moved  in  the 
ordinary  way.  The  bone  must  be  put  back  m  its 
normal  place  in  the  joint.  This  should  be  done  by  a 
physician,  unless  it  chances  to  be  one  of  the  small 
bones  in  the  finger,  which  almost  any  one  can  pull  back 
into  place  by  slightly  pulling  the  bones  apart  and  then 
slipping  the  dislocated  bone  into  position.  When  a  bone 
is  dislocated,  it  is  very  likely  that  some  of  the  connect- 
ing bands  or  ligaments  may  be  strained  or  slightly  torn. 
A  sprain  is  a  tear  or  strain  in  one  or  more  of  the 
ligaments  of  a  joint,  A  sprain  is  common  in  con- 
nection with  dislocated  joints,  but  it  occurs  frequently, 
also,  when  there  is  no  dislocation.  A  violent  strain  at 
any  joint  may  cause  such  a  pulling  on  the  ligaments  as 
to  injure  them  and  produce  a  sprain.  The  injury  is 
sometimes  very  slight  and  sometimes  very  great.  A 
sprain  may  be  even  more  serious  than  a  dislocation  or  a 
broken  bone,  requiring  a  longer  time  to  heal.  In  case 
of  a  sprain,  the  joint  should  be  placed  in  a  comfortable 
position.  Water,  as  hot  as  can  be  endured,  should 
then  be  applied,  and  this  should  be  followed  by  cold 
water.  The  joint  should  be  bound  tightly  with  band- 
ages. It  is  wise,  of  course,  to  rest  the  joint,  but  it  is 
not  wise  to  keep  it  perfectly  still  during  the  healing 
process,  lest  it  be  stiff  for  a  long  time.  The  sprain 
will  be  more  quickly  healed  if,  beginning  say  a  day  or 


FRAMEWORK  AND  MOTION  OF   THE  BODY      141 


two  after  the  accident,  the  joint  is  used  a  little  each 
day. 

THE  MUSCLES 

A  large  part  of  the  food  we  eat  is  used  to  enable  us 
to  move.  The  motions  of  the  body  are  brought  about 
by  the  muscles.  The  lean  part  of  meat  consists  of 
muscles,  and  the  muscles  in  our  bodies  are  very  similar 
in  appearance  to  lean  beef,  as  it  comes  from  the  market. 
The  joints,  ligaments,  and  tendons  of  themselves  would 
be  unable  to  move  the  body.  It  is  through  the  muscles 
that  the  power  is  applied. 

Structure  of  a  Muscle.  —  To  understand  the  structure 
of  a  muscle,  let  us  look  at  the  one  in  the  front  part  of 
the  upper  arm,  known 
as  the  biceps,  which  we 
see  represented  in  Fig- 
nire  55.  The  biceps 
muscle,  as  the  figure 
shows,  is  a  rather  long 
mass  of  flesh,  large  in 
the  middle  but  taper- 
ing at  the  two  ends. 
The  middle  part  is 
made  up  of  reddish 
flesh,  and  is  the  mus- 
cle itself.  At  the  ends 
firm,  white  bands  or  cords,  which  neither  contract  nor 
expand,  connect  the  muscle  with  the  bones.  These 
are  tendons  or  cords. 


(Jfno 


FIG.  65. 

Showing  the  method  of  attachment  of 
the  biceps  muscle  to  more  the  fore- 
arm. 


142  PHYSIOLOGY  AND  HYGIENE 

Most  of  the  muscles  in  the  body  are  connected  with 
bones  by  tendons.  The  tendons  differ  in  length,  some 
of  them  being  very  short.  A  series  of  such  cords  at 
the  wrist  extends  from  the  arm  to  the  fingers,  and  at 
the  ankle  from  the  leg  to  the  toes. 

If  we  grasp  the  left  arm  just  below 
the  elbow  with  the  right  hand,  and 
then  open  and  close  the  fingers  of  the 
left  hand,  we  can  feel  the  motion 
of  the  arm  muscles.  These  muscles 
move  the  fingers,  and  are  connected 
with  them  by  the  long  tendons  which 
pass  to  the  finger  bones.  If  we  clinch 
the  fingers  of  the  left  hand  and  grasp 
the  wrist  with  the  right  hand,  we  can 
feel  how  tightly  the  tendons  are 
stretched  as  they  pass  along  the  front 
of  the  wrist.  Figure  56  shows  their 
arrangement. 

A  muscle  seems  to  be  a  solid  mass 
FIG.  56.  °f  flesh.     If  we  examine  it  under  a 

Showing  the  muscles  microscope,  however,  we  find  that  it  is 
and  tendons  of  the  u  made  f  an  immense  number 
arm.  / 

of  threads  or  muscle  fibers,  as  they  are 

called.  We  can  see  how  the  fibers  are  arranged,  from 
Figures  57  and  58.  These  muscle  fibers  are  too  small 
to  be  seen  without  a  microscope.  They  run  lengthwise 
in  the  muscle,  and  they  are  very  numerous.  They  are 
bound  together  by  a  thin,  delicate  substance  which 
fastens  them  firmly  to  one  another. 


FRAMEWORK  AND  MOTION  OF   THE  BODY      143 

Great  numbers  of  minute  blood  vessels  run  in  and 
out  among  the  fibers,  furnishing  the  muscle  with  its 
nourishment,  as  shown  in  Figure  36,  facing  page  108. 
These  blood  vessels  are  the  capillaries  which,  as  we 
learned,  receive  the  blood  when  it  leaves  the  arteries, 
before  its  return  to  the  heart  by  way  of  the  veins.  The 
walls  of  the  capillaries  are  so  thin  that  the  food  which  is 


Muscle 
fibers 

FIG.  57.  — A  BIT  OF  MUSCLE.         FIG.  58.  — A  BIT  OF  MUSCLE. 
Slightly  magnified.  Highly  magnified,  showing  muscle 

fibers. 

in  the  blood  passes  through  them  to  the  muscle  fibers, 
giving  them  power  to  move  and  building  them  up. 

Involuntary  Muscles.  —  There  is  another  kind  of 
muscle  which  we  hear  less  about.  These  muscles  are 
called  involuntary  muscles,  because  we  do  not  consciously 
control  them.  The  most  important  are  those  which  form 
the  walls  of  the  stomach  and  intestines  and  propel  the 
food,  and  those  which  contract  and  expand  the  arteries 


144  PHYSIOLOGY  AND  HYGIENE 

and  thus  regulate  the  flow  of  blood.  These  muscles  are 
very  different  in  appearance  from  the  ones  we  have 
just  described,  but  they  also  are  made  of  microscopic 
fibers,  bound  together  in  flat  masses.  They  are  much 
more  sluggish  in  their  action  than  the  other  muscles, 
and  we  not  only  have  no  control  over  them,  but  we 
are  not  even  conscious  of  their  action.  But  since  they 
drive  the  food  along  the  intestines  and  control  the  flow 
of  blood,  they  are  of  great  importance. 

The  Contraction  of  a  Muscle.  —  If  we  stretch  a  rubber 
band,  it  becomes  longer  and  thinner  ;  when  we  let  go 
of  the  ends,  it  shortens  and  becomes  as  thick  as  before. 
In  somewhat  the  same  way  the  muscles  of  the  body 
are  shortened,  the  muscle  growing  thicker  as  it  con- 
tracts. If  we  clinch  the  left  fist,  grasp  the  left  arm 
above  the  elbow  with  the  right  hand,  and  then  lift 
the  forearm  forcibly,  we  find  that  the  biceps  mus- 
cle becomes  larger  and  harder  as  the  hand  is  raised. 
After  the  arm  has  been  lifted,  the  muscle  may  hold  it 
up  for  a  time,  but  to  do  so  constant  effort  is  required. 
The  moment  we  relax  the  effort  the  arm  falls  of  its 
own  weight.  To  lift  the  arm  the  muscle  must  be  con- 
tracted, but  no  muscular  effort  is  required  to  lower  it. 

There  is,  however,  on  the  back  of  the  arm,  as  shown 
in  Figure  55,  a  muscle  which  acts  in  the  opposite  way 
from  the  biceps.  If  this  muscle  shortens  or  contracts, 
it  pulls  the  arm  down,  stretching  the  biceps,  as  may  be 
understood  from  Figure  55.  The  two  muscles  thus 
form  a  pair  opposed  to  each  other  ;  when  one  of  them 
contracts,  the  other  is  lengthened.  One  lifts  the  arm 


FRAMEWOKK  AND  MOTION  OF  THE  BODY   145 

up,  and  the  other  straightens  it.  It  is  the  contraction 
of  a  muscle  that  produces  motion  or  action. 

What  makes  the  Muscles  contract.  —  In  addition  to 
the  blood  vessels  in  each  muscle,  there  is  connected 
with  it  a  white  cord  —  a  nerve.  This  nerve  is  larger  in 
the  large  muscles  than  in  the  small  ones.  The  nerve 
is  made  up  of  nerve  fibers,  and  each  muscle  fiber  re- 
ceives its  nerve  fiber.  All  of  these  fibers  are  connected 
with  the  spinal  cord,  and  through  the  spinal  cord,  with 
the  brain. 

Why  are  the  muscles  connected  with  the  brain?  Just 
this  :  The  nerves  serve  much  the  same  purpose  as 
electric  wires.  The  muscles  never  contract  of  their 
own  accord  any  more  than  an  electric  bell  will  ring 
itself.  To  ring  the  bell  we  must  press  a  button.  This 
sends  an  electric  current  through  the  wire  and  causes 
the  bell  to  ring.  In  about  the  same  way  the  muscles 
of  the  body  act,  when  the  proper  kind  of  message 
comes  to  them.  If  the  current,  or  stimulus,  as  it  is 
called,  never  comes,  the  muscle  will  remain  quiet  for- 
ever. The  stimulus  is  given  to  the  muscle  through 
the  nerves.  The  brain,  which  is  the  central  station 
for  all  kinds  of  action,  is  able  to  send  stimuli  down 
to  the  muscles  through  these  thousands  of  little  threads, 
and  when  the  muscles  get  the  message  they  contract. 
The  involuntary  muscles  are  excited  into  action  in 
the  same  way,  for,  although  we  do  not  will  to  move 
them,  the  brain  sends  stimuli  to  them  as  it  does  to  the 
other  (voluntary)  muscles. 

This  power  which  the  brain  has  over  the  muscles 


146  PHYSIOLOGY  AND  HYGIENE 

is  very  wonderful.  Not  only  can  the  brain  cause 
a  single  muscle  to  contract  at  any  time,  but  it  can 
cause  many  muscles  to  act  together,  either  in  connec- 
tion with  one  another  or  separately.  For  example,  when 
a  boy  throws  a  stone,  he  lifts  his  arm,  closes  his  fingers 
about  the  stone,  presses  one  foot  hard  against  the 
ground,  and  sets  his  body  firmly  to  assist  in  the  throw- 
ing ;  then  he  must  quickly  contract  the  muscles  of  the 
arm  and  shoulder,  and  loosen  the  stone  from  his  fingers. 
In  all,  from  fifty  to  a  hundred  muscles  must  be  con- 
tracted at  nearly  the  same  time. 

v/The  boy  does  not  realize  that  he  is  using  such  a 
wonderful  machine,  or  even  that  he  is  contracting 
muscles.  He  simply  thinks,  "  I  will  throw  the  stone," 
and  the  brain  gives  the  proper  order  to  the  numerous 
muscles.  The  message  must  be  sent  to  each  of  these 
muscles  at  the  same  time,  and  must  cause  each  to 
contract  just  the  right  amount.  If  the  brain  should 
make  a  mistake,  and  cause  some  muscles  to  contract 
too  much  or  not  enough,  the  stone  would  go  wide  of 
the  mark.  This  really  happens  many  times  when  the 
boy  is  learning  to  throw  straight.  We  say  that  "  prac- 
tice makes  perfect";  that  is,  the  boy  must  learn  how 
to  throw  the  stone  just  where  he  wants  it  to  go.  In 
other  words,  the  brain  must  learn  how  to  make  the 
muscles  work  in  the  proper  way. 

Number  and  Positions  of  the  Muscles.  —  The  fleshy 
part  of  our  bodies  is  made  up  of  a  little  more  than 
five  hundred  muscles.  They  differ  in  size  and  shape. 
Most  of  them  are  fastened  to  at  least  two  bones,  so 


FRAMEWORK  AND  MOTION  OF  THE  BODY       147 


that  as  the  muscles  are  contracted  the  bones  are  moved. 
Figures  56  and  59  show  how  the  muscles  are  arranged 
in  the  body,  though  compara- 
tively few  are  represented 
here.  The  various  muscles 
are  so  attached  to  the  bones 
that  they  can  be  moved  in 
all  the  directions  that  the 
joints  permit.  We  can  bend 
the  arm  or  straighten  it ;  we 
can  move  it  to  either  side  or 
turn  it  around,  each  motion 
being  produced  by  a  different 
set  of  muscles. 

Muscle  Growth.  —  It  is  a 
peculiarity  of  muscles  that 
the  more  they  are  used,  the 
stronger  they  grow.  The 
blacksmith,  because  he  con- 
stantly swings  his  heavy 
hammer,  develops  very  strong 
muscles  in  his  arms.  When 
a  person  learns  to  ride  a 
bicycle,  he  finds  that  certain 
muscles  of  his  legs  are  weak, 
but,  as  he  continues  the  exer- 
cise, the  muscles  become 
stronger,  until  he  can  climb 
even  high  hills  without  any  great  strain.  One  set  of 
pmscles,  however,  should  not  be  developed  and  others 


FIG.  59. — THE  SURFACE  MUS- 
CLES OF  THE  BODY. 


148  PHYSIOLOGY  AND  HYGIENE 

neglected.  The  man  who  has  all  his  muscles  moderately 
well  developed  is  stronger  and  more  healthy  than  the 
one  who  has  highly  developed  his  arm  muscles  with- 
out exercising  equally  the  other  muscles  of  the  body. 

If  muscles  are  not  used,  they  become  small  and 
weak.  If  a  muscle  were  left  idle  for  a  few  months,  it 
would  lose  much  of  its  power,  so  that  we  could  not  use 
it  at  all.  Children  in  their  active  play  ordinarily  use 
all  their  muscles,  so  that  they  develop  evenly.  But 
as  people  grow  older,  certain 'muscles  are  used  less  and 
less.  We  take  the  trolley-car  and  the  elevator  to  save 
the  trouble  of  walking:  as  a  result,  we  find  that  we 
cannot  walk  so  far  as  we  could  a  few  years  ago.  We  use 
the  right  hand  in  our  work  rather  than  the  left,  and 
the  left  hand  is  weaker  and  less  skillful.  We  sit  in  a 
comfortable  easy-chair  until  the  muscles  of  the  back  are 
weakened,  and  as  a  result  we  cannot  sit  upright  for 
any  length  of  time  without  fatigue.  Although  we  really 
want  our  bodies  to  be  well  developed  and  vigorous,  we 
get  into  these  habits  of  neglecting  the  muscles  from 
carelessness. 

Exercise.  — •  It  is  worth  our  while  to  make  special 
efforts  to  use  all  the  muscles  of  the  body.  If  we  find 
that  certain  muscles  are  weak,  those  are  the  ones  that 
we  should  take  pains  to  exercise.  Too  frequently  we 
do  the  reverse.  If  we  find  something  that  is  particularly 
hard,  for  us  to  do,  perhaps  sweeping  or  sawing  wood, 
that  is  just  what  we  should  do  every  day,  until  the 
muscles  are  so  developed  that  we  find  it  easy  work. 

In  large  cities  the  chances  that  young  people  have 


FRAMEWORK  AND  MOTION  OF  THE  BODY    149 

for  muscular  exercises  are  limited.  For  this  reason 
gymnasiums  have  been  erected  in  cities,  and  especially 
in  schools  and  colleges.  The  person  who  commonly 
needs  the  most  urgent  advice  to  take  exercise  is  the 
boy  or  girl  who  is  ambitious  to  become  a  scholar. 
He  prefers  to  spend  all  his  time  at  his  books,  and  is 
not  willing  to  give  even  a  little  time  each  day  to  ac- 
tive exercise.  He  should  remember  that  the  person 
who  studies  all  the  time  is  likely  to  be  outstripped 
by  the  one  who  studies  and  plays  as  well.  Many 
students  break  down  because  they  do  not  take  sufficient 
exercise. 

Out-of-door  games  afford  the  best  possible  exercise, 
since  these  not  only  develop  the  muscles  but  give  the 
player  fresh  air  and  recreation  at  the  same  time.  Such 
games  as  baseball,  golf,  and  tennis  are  excellent.  Bicy- 
cling is  good  exercise,  though  "  century  runs  "  and  very 
fast  riding  are  dangerous,  and  the  habit  of  bending 
over  the  handle  bars  makes  one  liable  to  what  is  known 
as  bicyclers'  stoop.  Brisk  walking  and  running  are 
very  good  exercise  ;  strolling  can  hardly  be  called  exer- 
cise at  all,  although  in  other  ways  a  quiet  walk  in  the 
open  country  is  beneficial. 

The  royal  maxim  for  perfect  body  development  is : 
A  perfect  body  requires  the  development  of  all  muscles; 
all  powers  unused  are  weakened. 

So-called  "Stimulants."  — Some  people  have  the  mis- 
taken idea  that  they  can  increase  their  muscular  power 
by  using  what  are  wrongly  called  stimulants,  generally 
meaning  some  form  of  liquor.  For  a  short  time  after  a 


150  PHYSIOLOGY  AND  HYGIENE 

person  has  taken  the  alcohol  there  may  be  a  slight 
increase  of  muscular  power,  but  a  decrease  of  such 
power  follows  very  soon,  so  that  there  is  in  the  end  an 
actual  loss  of  power.  If  alcohol  is  used  in  any  consid- 
erable amounts,  there  is  a  great  weakening  of  muscular 
power. 

The  use  of  alcohol  will  unfit  any  boy  for  good  work 
in  an  athletic  contest.  Under  no  conditions  does  alco- 
hol enable  an  athlete  to  do  his  best.  It  has  a  tendency 
both  to  weaken  the  muscles  and  to  dull  the  senses. 
Boys  and  young  men  sometimes  make  the  mistake  of 
trying  to  "  brace  themselves  up  "  for  a  contest  by  the 
use  of  alcohol.  Professional  athletes  know  enough  to 
let  alcohol  alone  under  these  circumstances. 

QUESTIONS 

1.  Of  what  is  the  framework  of  the  body  made  ?    What  is 
this  framework  called? 

2.  What  organs  are  inclosed  in  the  skull  ? 

3.  How  are  the  long  bones  of  the  arm  and  leg  constructed? 

4.  Of  what  are  bones  made  ? 

5.  If  we  did  not  have  enough  lime  in  our  food,  what  effect 
would  it  have  on  the  bones? 

6.  How  do  children's   bones  differ  from  those  of   a  grown 
person  ? 

7.  What  happens  to  the  bones  if  there  is  unnatural  pressure 
upon  them  ? 

8.  What  are  the  results  of  wearing  tight  clothing  ? 

9.  How  are  broken  bones  repaired  ? 

10.  What  is  cartilage  ?     Where  is  it  found  ? 

11.  What  two  kinds  of  joints  are  there  in  the  body? 

12.  How  is  a  hinge  joint  made  ? 


FRAMEWORK   AND  MOTION  OF   THE  BODY    151 

13.  Mention  all  of  the  kinds  of  supporting  and  connecting  tis- 
sues found  in  the  body. 

14.  What  is  a  ligament  ? 

15.  What  is  a  tendon? 

16.  How  does  the  ball-and-socket  joint  differ  from  the  hinge 
joint  ? 

17.  How  are  the  bones  in  a  ball-and-socket  joint  fitted  and 
fastened  together  ? 

18.  Why  do  we  have  a  hinge  joint  at  the  knee  instead  of  a  ball- 
and-socket  joint? 

19.  Why  do  we  need  a  ball-and-socket  joint  at  the  shoulder? 

20.  What  is  meant  by  dislocation  ? 

21.  What  is  a  sprain  ? 

22.  What  are  the  parts  of  a  muscle  ? 

23.  How  is  a  muscle  contracted? 

24.  How  is  the  muscle  contraction  controlled  by  the  brain  ? 

25.  Why  is  it  that  a  person  falls  over  if  he  suddenly  faints  or 
dies,  when  in  a  sitting  or  standing  position? 

26.  What  effect  have  exercise  and  lack  of  exercise  upon  the 
muscles  ? 

27.  What  are  the  best  kinds  of  exercise  ? 

28.  Give  some  examples  from  your  own  observation  of  loss  of 
power  from  disuse. 

29.  What  is  the  effect  of  alcohol  upon  the  muscles  ? 


152 


PHYSIOLOGY   AND  HYGIENE 


A  LIST  OF  THE  CHIEF  BONES  IN  THE  BODY 


All  forming  the  skull. 


The  nasal  bones. 
The  frontal  bones. 
The  parietal  bones. 
The  occipital  bone. 
The  mandible  or  lower  jaw    j 
The  sternum  or  breastbone.  1   Forming  the 

The  ribs  from  the  backbone  to  the  sternum.  J        thorax. 
The  vertebrae  forming  the  spine. 

The  sacrum  at  the  lower  end  of  the  vertebrae  between  the  hips. 
The  coccyx,  a  small  piece  of  bone  below  the  sacrum. 
The  scapula  or  shoulder  blade. 
The  clavicle  or  collar  bone. 
The  humerus,  from  the  shoulder  to  the  elbow. 
The  radius  and  the  ulna,  from  the  elbow  to 
the  wrist. 

The  carpals  or  wrist  bones,  eight  in  number. 
.  The  metacarpals,  from  the  wrist  to  the  fingers. 
The  phalanges  or  finger  bones. 

The  ilium. 

Fused  together  to  form  the  hip  bone,  or  pelvic 


The  leg. 


The  arm. 


The  pubis. 

The  ischium. 

The  femur,  from  hip  to  knee. 

The  tibia  and  fibula,  from  knee  to  ankle. 

The  tarsals  or  ankle  bones. 

The  metatarsals,  from  ankle  to  the  toes. 

The  phalanges,  or  bones  of  the  toes. 


CHAPTER  VII 

THE     KIDNEYS     AND     THE    SKIN    AND     THEIR 
DUTIES 

WASTE  PRODUCTS 

Use  of  Food  by  Muscles. — A  muscle  is  like  a  little 
steam  engine  which  cannot  work  except  when  burning 
fuel.  We  have  seen  how  the  different  foods  are  carried 
throughout  the  body  by  the  blood.  When  these  foods 
reach  the  capillaries,  the  muscle  fibers  take  what  they 
need  for  their  use.  The  proteids  serve  especially  to 
make  new  muscle  tissue,  which  is  constantly  needed 
to  take  the  place  of  that  used  up  by  the  work  of  the 
muscle.  The  proteid  or  building  foods  are  also  needed 
to  repair  any  injury  that  may  have  come  to  the  muscle, 
and  to  supply  the  new  material  needed  when  the 
muscle  is  developing  and  growing.  The  sugars  and 
fat,  with  some  of  the  proteids,  simply  furnish  heat  and 
force  ;  in  other  words,  they  are  fuel  foods.  The  food 
is  oxidized  in  the  muscles  by  means  of  the  oxygen 
brought  by  the  blood.  As  a  result,  force  is  developed 
to  enable  the  muscles  to  contract,  and  heat  is  produced 
to  warm  the  body. 

Waste  Products  of  Muscle  Action. — When  coal  or 
other  fuel  is  burned,  or  oxidized,  smoke  and  gas  pass 
off  into  the  air  and  ashes  are  left  in  the  grate.  These 

153 


154  PHYSIOLOGY  AND   HYGIENE 

are  waste  products,  because  they  are  not  used  and  can- 
not be  used  for  heating.  When  the  fuel  food  of  the 
body  is  oxidized  in  the  muscles  and  tissues,  waste 
products  are  left,  which  are  of  no  further  use.  These 
are  carbon  dioxide,  water,  and  other  substances. 
These  waste  products  must  be  gotten  rid  of.  We 
have  already  seen  how  the  carbon  dioxide  is  taken 
away  by  the  blood,  and  breathed  out  of  the  body  from 
the  lungs.  We  know  also  that  some  water  goes  out 
in  the  breath.  A  larger  quantity  of  water  passes  off 
through  the  skin  and  from  the  kidneys,  as  we  shall 
see  presently.  The  third  waste  product,  known  as 
urea,  is  taken  from  the  blood  by  the  kidneys,  and 
finally  leaves  the  body  in  the  urine. 

A  large  proportion  of  the  food  we  eat  is  taken  by  the 
muscles  to  supply  muscular  force.  Some  of  it  is  used 
in  the  brain,  a  small  amount  in  the  glands,  and  certain 
quantities  in  every  active  part  of  the  body.  But,  al- 
though the  uses  made  of  the  food  may  differ  in  the 
various  places,  the  same  oxidation  takes  place,  and  the 
same  waste  products  always  result. 

Secretions  and  Excretions.  —  The  materials  produced 
by  the  body  are  generally  classified  under  two  heads. 
Those  like  carbon  dioxide  and  urea  are  simply  waste 
products  and  of  no  use  at  all.  They  are  generally 
called  excretions.  But  some  of  the  materials  are  pro- 
duced for  special  purposes.  For  example,  the  gastric 
glands  in  the  stomach  produce  gastric  juice  to  aid 
digestion,  and  the  salivary  glands  produce  saliva  for  the 
same  purpose.  Materials  which  are  thus  of  use  to  the 


KIDNEYS  AND  SKIN  AND  THEIR  DUTIES      155 

body  are  called  secretions,  and  they  are  generally  pro- 
duced by  special  organs  called  glands.  We  have 
already  learned  of  several  of  these,  the  salivary  glands, 
the  gastric  glands,  and  the  pancreas. 

The  excretions  are  not  only  of  no  use,  but  if  allowed 
to  collect  in  the  body  they  act  as  poisons.  Hence  they 
must  be  gotten  rid  of  promptly. 

Some  of  them  can  pass  off  through  the  lungs  in  the 
breath,  and  some  from  the  skin  in  perspiration,  but 
some  are  disposed  of  in  other  ways. 

THE  KIDNEYS 

Urea  is  thrown  off  from  the  body  by  means  of  a  pair 
of  organs  called  the  kidneys.  Each  kidney  is,  in  a  grown 


FIG.  60. —  THE  KIDNEYS. 
The  one  on  the  right  is  cut  open  to  show  the  tubes  which  secrete  the 


urea. 


156  PHYSIOLOGY  AND  HYGIENE 

person,  some  four  inches  long  and  one  and  a  half  inches 
wide.  The  kidneys  are  located  in  the  back  part  of  the 
abdomen,  just  below  and  behind  the  stomach,  and  close 
to  the  backbone.  Their  shape  is  indicated  in  Figure  60. 
A  large  artery  brings  the  blood  to  each  kidney,  as  the 
same  figure  shows,  and  a  large  vein  takes  the  blood 
away.  There  is  also  a  tube,  called  the  ureter,  that 
passes  from  the  kidney  to  the  bladder,  and  takes  away 
the  material  removed  from  the  blood  by  the  kidney. 

The  kidney  is  made  up  of  a  large  number  of  blood 
vessels,  together  with  a  series  of  small  tubes,  called 
kidney  tubules,  as  shown  in  Figure  60.  As  the  blood 
passes  through  the  kidney,  the  tubules  take  the  urea 
and  some  other  solid  matters  which  are  dissolved  in 
the  blood.  This  material,  together  with  considerable 
water,  which  is  also  taken  from  the  blood,  is  poured 
into  the  ureters,  and  passes  to  the  bladder  and  then  out 
of  the  body. 

THE  SKIN 

Although  mainly  of  use  as  a  covering  for  the  body, 
the  skin  has  special  functions  of  its  own.  It  serves  as  a 
means  for  the  passing  out  of  waste  and  for  regulating 
the  heat  of  the  body.  A  healthy  skin  is  absolutely 
necessary  if  the  body  is  to  be  in  good  condition.  Slug- 
gishness or  improper  action  of  the  skin  in  its  work  is 
likely  to  cause  sickness. 

Structure  of  the  Skin.  —  The  skin  is  a  thick  sheet  like 
a  close-fitting  garment,  covering  the  entire  body.  A 
grown  person  has  about  sixteen  square  feet  of  skin. 


KIDNEYS   AND   SKIN  AND   THEIR   DUTIES      157 


Epidermis 


Wermis 


The  average  thickness  is  about  one  sixteenth  of  an 
inch,  though  it  is  thinner  in  some  places  than  others. 
It  is  thickest  on  the  soles  of  the  feet  and  the  palms  of 
the  hands. 

If  we  take  a  thin 
slice  of  skin  and 
look  at  it  through 
a  microscope,  we 
find  that  it  has  two 
layers,  one  outside 
of  the  other,  as 
shown  in  Figure  61. 
The  outer  layer  is 
called  the  epidermis, 
and  the  inner  layer 
is  the  dermis.  We 
can  stick  a  pin 
through  the  epider- 
mis without  feeling 
it,  but  the  instant 
the  point  enters  the 
dermis  we  feel  pain. 
All  the  epidermis, 
except  a  thin  layer 
on  the  inner  side,  is  practically  lifeless,  and  contains 
neither  nerves  nor  blood  vessels.  The  dermis  is  full 
of  blood  vessels  and  nerves,  and  is  very  sensitive. 

The  Epidermis.  —  The  epidermis,  though  lifeless  at 
the  outer  surface,  is  continually  growing  on  the  inside, 
where  it  is  in  contact  with  the  dermis.  Very  often 


FIG.  61.  — A  SECTION  OF  A  BIT  OF  SKIN. 

Highly  magnified. 


158  PHYSIOLOGY  AND   HYGIENE 

when  we  look  at  our  hands  we  can  see  one  or  more  bits 
of  loose  skin  which  may  be  pulled  off  without  harm. 
The  outside  skin  is  all  the  time  being  thus  worn  or 
rubbed  off,  bit  by  bit,  and  it  keeps  growing  from  the 
inside.  The  epidermis  is  so  firmly  attached  to  the 
dermis  that  the  two  are  not  easily  separated.  Occasion- 
ally we  burn  a  spot  on  the  finger,  or  are  severely  sun- 
burned, so  that  blisters  appear,  that  is,  a  little  watery 
material  has  gathered  between  the  epidermis  and  the 
dermis.  If  the  blister  is  broken  and  the  outer  skin 
removed,  the  dermis  is  exposed.  This  is  always  sen- 
sitive and  tender. 

Thick  Parts  of  the  Epidermis.  —  A  boy  who  is  an  en- 
thusiastic ball-player  is  very  proud  of  certain  bunches  on 
the  palms  of  his  hands,  called  callosities.  The  constant 
rubbing  and  striking  of  the  ball  causes  the  epidermis 
to  grow  more  rapidly  at  these  spots  than  elsewhere,  and 
so  it  becomes  thicker.  Any  part  of  the  skin  that  has 
an  extra  amount  of  use  grows  thicker  than  the  rest,  this 
being  nature's  means  of  protection  against  injury. 

If  we  wear  tight  or  poorly  fitting  shoes  that  con- 
stantly rub  the  toes,  round  bunches  called  corns  are 
formed  by  the  thickening  of  the  skin.  We  can  pre- 
vent the  growth  of  corns  by  wearing  shoes  large 
enough  not  to  pinch  the  toes,  and  yet  snug  enough 
not  to  chafe  the  feet.  It  is  difficult  to  get  rid  of  corns 
after  they  have  once  formed,  so  it  is  wise  to  avoid 
the  great  discomfort  which  they  cause  by  taking  proper 
care  of  the  feet.  Children  who  go  barefooted  in  the 
summer  rarely  have  either  corns  or  deformed  toes, 


KIDNEYS  AND   SKIN  AND  THEIR  DUTIES      159 


-Hair 


Occasionally  certain  parts  of  the  skin  grow  too  thick, 
causing  what  are  known  as  warts.  Children  are  apt  to 
be  superstitious  about  these  growths,  because  they  come 
and  go  so  suddenly.  Some  children  believe  that  warts 
result  from  handling  toads,  and  that  they  can  be  cured 
by  the  use  of  certain  charms,  both  of  which  are  absurd 
ideas.  If  a  wart  grows 
large  enough  to  be 
really  troublesome,  it 
can  be  burned  off  with 
acid,  but  under  ordi- 
nary conditions  warts 
had  better  be  let  alone. 
They  will  disappear 
without  assistance  in 
time. 

Hair.  —  Nearly  all 
parts  of  the  skin  are 
covered  with  hair, 
which  is  an  outgrowth 


from  the  epidermis. 
Figure  62  shows  that 
each  hair  extends  down 


Oil 

Gland 
~Hair 
Follicle 


Hair  Pa  pi  I  la 
Grozny  Cells 

FIG.  62.— A  HAIR. 
through  the  skin  into  a 

Showing  its  root  and  follicle. 

little   pocket.      This  is 

called  the  hair  follicle.  A  very  small  mound,  or 
papilla,  which  is  the  place  where  the  hair  grows,  is 
located  at  the  bottom  of  the  pocket.  The  hair  is  thus 
constantly  growing  at  its  root,  and  being  thus  pushed 
out  of  the  pocket.  In  other  words,  the  hair  grows  from 


160  PHYSIOLOGY  AND  HYGIENE 

the  roots,  not  from  the  ends.  If  a  hair  is  pulled  out, 
the  little  mound  at  the  root  usually  keeps  on  sending 
out  more  substance,  so  that  a  new  hair  grows  to  take 
the  place  of  the  old  one.  If  the  whole  follicle,  includ- 
ing the  mound  at  the  bottom,  is  destroyed,  no  new  hair 
will  grow. 

Each  hair  is  supplied  with  oil  from  tiny  oil  glands. 
These  open  into  the  follicle  from  the  sides,  as  shown  in 
Figure  62.  They  produce  an  oily  substance  that  mois- 
tens the  outside  of  the  hair,  keeping  it  soft  and  flexible. 
If  the  hair  is  brushed  frequently,  the  oil  will  be  distrib- 
uted over  it,  so  that  no  hair  oil  need  be  used  to  keep  it 
in  good  condition.  We  should  never  brush  the  hair 
with  anything  but  a  soft  hairbrush.  Wire  brushes  are 
likely  to  scrape  the  scalp  so  that  the  follicles  may  be 
injured,  and  they  may  pull  out  the  hair. 

Hair  is  lifeless  and  has  no  sensations.  If  we  place  a 
hand  upon  the  head,  we  may  feel  the  touch,  but  the 
feeling  is  not  in  the  hair  itself ;  we  feel  the  pushing  of 
the  hair  against  the  nerves  in  the  skin.  We  say  that  a 
cat's  whiskers  are  very  sensitive.  The  feeling  is  not  in 
the  hairs  themselves,  but  in  the  very  delicate  nerves 
about  the  roots. 

Hair  grows  on  all  parts  of  the  body  excepting  the 
palms  of  the  hands  and  the  soles  of  the  feet.  In  some 
places  it  hardly  more  than  reaches  the  surface  and  is 
therefore  so  short  that  we  do  not  notice  it.  Certain 
animals,  like  the  cat  and  the  dog,  have  very  thick 
hair,  which  serves  as  a  protection  and  covering  for 
the  skin.  The  hair  of  human  beings  is  of  no  particular 


KIDNEYS   AND   SKIN  AND   THEIR  DUTIES      161 


use  except  for  ornament  and  for  its  protection  to  the 
head. 

The  hair  of  the  head  has  a  tendency  to  fall  out  and 
produce  baldness.  This  is  especially  true  of  the  hair 
of  men.  Just  why  this  is  the  case  physicians  do  not 
know.  Some  think  that  it  is  due  largely  to  the  habit 
of  wearing  heavy  hats  with  stiff  rims  which  bind  the 
scalp  ;  they  advise  the  use  of  loose,  cool  hats.  Others 
are  of  the  opinion  that  "shampooing"  the  hair  with 
the  aid  of  diluted  ammonia  and  soap,  or  other  sub- 
stances, causes  baldness.  It  is  necessary,  however,  to 
keep  the  hair  clean,  and  it  may  safely  be  washed  with 
water  containing  a  little  soap.  The  soap  should  be 
carefully  rinsed  off  and  the  hair  thoroughly  dried. 
Hair  oil  and  hair  restorers  of  all  kinds  should  be 
avoided. 

Toe  Nails  and  Finger  Nails.  —  The  toe  nails  and  finger 
nails  are  parts  of  the  epidermis  developed  in  a  special 
way.  Figure  63  represents 
a  cross  section  of  a  finger, 
showing  the  nail.  The 
purpose  of  the  nails  is  to 
protect  the  fingers  and 
toes.  They  also  help  to 
beautify  the  hand,  and 
they  aid  us  in  picking  up 
small  objects  by  enabling 
us  to  grasp  them  firmly. 

The  nail  grows  outward  from  the  root  at  the  base, 
and  unless  the  root  is  injured,  the  growth  continues  as 


Npil 


FIG.  63. — A  SECTION  THROUGH 

THE   TlP   OF    THE   FlNGER. 

Showing  the  nail. 


162  PHYSIOLOGY  AND  HYGIENE 

long  as  we  live.  The  white  "  half  moon  "  at  the  lower 
edge  is  where  the  nail  is  new  and  quite  thin.  If  a  nail 
is  injured,  it  sometimes  comes  off.  A  new  one  will 
grow  in  its  place,  unless  the  root  has  been  destroyed. 
We  all  dislike  finger  nails  that  are  grimy  or  dirty  at  the 
ends.  They  should  be  kept  clean  and  neatly  trimmed 
with  a  knife  or  scissors.  They  should  be  cut  only  at 
the  ends ;  neither  the  surface  of  the  nail  nor  the  skin 
covering  the  root  should  be  scraped  or  cut. 

Some  young  people  form  the  habit  of  biting  the 
nails.  This  is  likely  to  injure  the  shape  of  the  fingers, 
besides  rendering  the  person  disagreeable  to  all  with 
whom  he  comes  in  contact.  While  various  reminders 
may  be  employed  to  aid  in  overcoming  the  habit,  such 
as  some  bitter  substance  placed  upon  the  nails,  the 
difficulty  should  be  conquered  by  the  exercise  of  will 
power. 

The  Dermis.  —  The  dermis,  shown  in  Figure  61,  is 
thicker  than  the  epidermis,  and  is  very  different  in 
structure.  It  consists  principally  of  a  mass  of  fibers, 
running  in  every  direction.  The  fibers  are  packed 
close  together  on  the  side  next  to  the  epidermis,  but 
they  are  less  dense  near  the  muscles,  which  lie  below 
the  skin.  Tiny  fat  cells  are  found  between  the  fibers, 
as  shown  in  Figure  61.  The  dermis  is  full  of  blood 
vessels,  so  that,  when  cut,  it  always  bleeds.  It  is  also 
very  sensitive,  because  of  the  many  nerves  it  contains. 
Some  of  these  nerves  are  particularly  sensitive  to  heat 
and  cold. 


KIDNEYS  AND  SKIN  AND   THEIR  DUTIES     163 


FUNCTIONS  OF  THE  SKIN 

As  a  Protection.  —  The  epidermis  is  made  of  flat, 
scalelike  cells,  packed  together  so  closely  that  they  are 
a  very  great  protection  to  the  flesh  beneath.  Some 
of  the  cells  may  be  seen  in  Figure  61.  We  can  plunge 
the  hand  into  poisons  without  injury,  because  the  sub- 
stances cannot  quickly  make  their  way  through  these 
cells.  Some  diseases,  as  we  shall  see  later,  are  caused 
by  microscopic  living  germs  getting  into  the  body  and 
growing  there.  The  epidermis  helps  to  protect  us 
from  such  diseases  by  keeping  out  the  germs.  If  they 
get  through  the  skin,  they  may  produce  sores,  boils, 
abscesses,  or  even  more  serious  troubles.  They  cannot 
pass  through  the  healthy  epidermis,  but  often  a  slight 
scratch  or  bruise  breaks  the  skin  enough  to  let  the 
germs  in.  As  a  result  of  the  growth  of  these  germs, 
the  scratch  becomes  inflamed  and  painful,  or  perhaps 
develops  a  sore  or  boil.  If  the  germs  can  be  kept  out, 
these  sores  will  not  appear.  Special  care  should  be 
taken  to  wash  all  cuts  and  bruises,  and  to  cover  them 
with  a  plaster  or  bandage  so  as  to  prevent  bacteria  from 
entering  where  the  epidermis  has  been  broken. 

As  an  Excreting  Organ. — When  we  have  been  taking 
vigorous  exercise,  or  on  a  very  warm  day,  small  drops 
of  moisture,  or  sweat,  appear  on  the  forehead,  the  nose, 
and  other  parts  of  the  body.  This  moisture  is  secreted 
by  the  sweat  glands,  of  which  we  have  about  two  and 
a  half  millions  in  our  skin. 


164  PHYSIOLOGY  AND  HYGIENE 

A  sweat  gland  is  too  small  to  be  seen  with  the  naked 
eye,  but  it  consists  of  a  tube  passing  through  the  epi- 
dermis, and  coiled  up  in  a  knot  on  the  inside,  as  shown  in 
Figure  61.  This  tube  secretes  the  sweat,  which  passes 
out  through  a  minute  hole  in  the  epidermis,  called  a 
pore,  and  is  discharged  upon  the  surface  of  the  skin, 
The  skin  of  the  whole  body  is  covered  with  these  tiny 


FIG.  64.  —  A  BIT  OF  SKIN  AS  IT  APPEARS  UNDER  A  MICROSCOPE. 
Showing  furrows  and  pores. 

pores,  each  leading  into  a  gland.  Though  they  are 
found  all  over  the  body,  there  are  more  of  them  upon 
the  forehead,  the  palms  of  the  hands,  and  the  soles  of 
the  feet  than  elsewhere.  If  we  look  at  the  skin  of  the 
ringers,  we  see  that  it  is  covered  with  irregular  furrows. 
If  we  compare  two  fingers,  we  find  that  the  furrows  are 
unlike.  The  pores  in  the  skin  of  the  fingers  are  along 
the  ridges  between  these  furrows,  as  shown  in  Figure 
64;  they  may  be  seen  with  a  magnifying  glass. 


KIDNEYS   AND  SKIN  AND  THEIR  DUTIES     165 

We  notice  the  sweat  only  when  it  appears  in  drops 
upon  the  surface  of  the  skin,  or  when  it  moistens  the 
clothing:  It  is  then  being  poured  out  of  the  glands  in 
especially  large  quantities,  but  the  glands  are  bringing 
it  out  all  the  time.  The  sweat  is  usually  evaporated 
as  fast  as  it  comes  to  the  surface,  not  becoming  visible, 
but  simply  moistening  the  skin.  If  we  hold  the  fingers 
close  to  a  cold  window  pane,  vapor  collects  on  the  glass. 
This  shows  that  water  is  evaporating  from  the  fingers, 
even  though  sweating  is  not  apparent. 

The  sweat  itself  is  principally  water,  though  small 
amounts  of  salt  and  other  substances  are  dissolved  in 
it.  In  fever,  sweating  is  reduced  very  much  or  stops 
entirely. 

As  a  Regulator  of  Body  Temperature.  — The  air,  both 
in  doors  and  out,  is  usually  cooler  than  our  skin.  The 
air  is  constantly  taking  heat  from  the  skin,  cooling  it 
and  the  blood  which  flows  near  the  surface.  The 
faster  the  blood  flows  through  the  skin,  the  faster  it 
is  thus  cooled  by  the  air. 

We  have  already  seen  that  the  skin  is  full  of  small 
blood  vessels.  These,  like  all  the  rest  of  the  blood 
vessels,  can  be  expanded  and  contracted  as  is  needed. 
If  the  body  is  producing  more  heat  than  usual,  brain 
centers  cause  the  blood  vessels  in  the  skin  to  expand; 
the  blood  then  flows  faster,  and  more  blood  is  cooled. 
If  the  body  is  not  producing  as  much  heat  as  usual, 
these  blood  vessels  are  made  to  contract.  The  blood 
is  thus  kept  away  from  the  surface  and  does  not  lose 
its  heat  by  giving  it  out  to  the  air.  By  opening  and 


166  PHYSIOLOGY   AND   HYGIENE 

closing  these  blood  vessels,  the  brain  is  able,  without 
our  knowledge,  to  increase  or  decrease  the  amount  of 
heat  lost  through  the  skin.  In  this  way  our  tempera- 
ture is  controlled  very  closely  and  accurately.  If  the 
body  is  too  warm,  the  blood  vessels  expand  and  let  the 
heat  out ;  if  too  cold,  they  contract  and  keep  it  in. 

The  nerves  that  are  sensitive  to  heat  and  cold  are 
located  in  the  skin.  When  the  warm  blood  pours 
through  the  skin,  it  warms  these  nerves  and  we  feel  the 
heat.  When  the  blood  vessels  contract,  so  that  the 
warm  blood  is  kept  away  from  the  skin,  these  nerves 
are  cooled  by  the  air  outside,  and  we  feel  cold.  On  a 
warm  day  we  feel  hot,  not  because  the  body  is  warmer 
than  usual,  but  because  the  warm  blood  is  flowing 
over  the  heat  nerves  in  the  skin.  The  body  has  practi- 
cally no  sensations  of  heat  and  cold  except  those  in  the 
skin  and  in  the  lining  of  the  mouth  and  the  digestive 
canal. 

Cold-blooded  Animals.  —  Frogs,  snakes,  and  certain 
other  small  creatures  are  called  cold-blooded  animals. 
The  amount  of  heat  produced  in  their  bodies  is  not 
very  great,  and  it  passes  off  as  fast  as  it  is  formed. 
The  cold-blooded  animals  are  never  much  warmer  than 
the  air  about  them.  On  a  warm  day  they  may  be  very 
warm,  on  a  cold  day  they  will  be  cold.  Such  animals 
are  usually  rather  sluggish,  especially  in  cold  weather. 

Warm-blooded  Animals.  —  The  amount  of  heat  pro- 
duced in  our  own  bodies,  and  in  those  of  such  animals 
as  dogs,  cats,  and  horses,  is  comparatively  large.  This 
heat  warms  the  blood  to  a  certain  temperature,  which 


KIDNEYS   AND   SKIN   AND   THEIR  DUTIES      167 

does  not  change  with  the  temperature  of  the  air,  but 
remains  about  the  same  all  through  life.  We  call  ani- 
mals whose  bodies  keep  the  same  temperature  warm- 
Hooded.  Their  blood  is  usually  warmer  than  the  air, 
although  on  a  hot  summer's  day  the  air  may  be  the 
warmer. 

To  keep  the  blood  at  this  temperature  requires  con- 
siderable activity  and  a  large  amount  of  food,  just  as 
a  considerable  quantity  of  coal  is  required  to  keep  our 
rooms  very  warm  in  winter.  A  cold-blooded  turtle 
may  live  for  six  months  without  eating  a  mouthful; 
its  activity  is  so  slight  that  the  small  amount  of  food 
stored  in  the  body  is  enough  to  sustain  life,  and  no 
heat  is  needed  to  warm  the  body.  A  warm-blooded 
animal,  on  the  other  hand,  must  not  only  have  a  large 
supply  of  food,  but  it  must  have  this  food  more  or  less 
regularly,  and  it  can  live  but  a  short  time  if  deprived 
of  the  regular  supply. 

When  we  are  in  perfect  physical  condition,  the  tem- 
perature of  our  bodies  is  almost  exactly  98^°  F.  If  the 
temperature  rises  above  this  point  or  falls  below,  it  is 
commonly  an  indication  of  ill  health.  We  feel  so  much 
warmer  on  a  hot  summer  afternoon  than  we  do  on  a 
winter  morning  that  it  seems  to  us  the  temperature  of 
our  bodies  cannot  be  the  same,  but  a  test  with  a  ther- 
mometer would  show,  in  both  cases,  just  the  98J°,  if  we 
are  well. 

Some  warm-blooded  animals  —  bears,  for  example  — 
sleep  throughout  the  winter.  When  thus  asleep  they 
burn  less  fuel  (food)  and  do  not  keep  warm ;  their  body 


168  PHYSIOLOGY  AND  HYGIENE 

temperature  falls  very  much,  but  this  does  them  no 
injury.  When  they  wake  in  the  spring,  they  begin  to 
burn  food  more  rapidly  and  are  soon  warmed  again. 
Such  animals  are  called  hibernating  animals. 

Regulation  of  Heat  by  the  Lungs.  — The  skin  is  aided 
in  regulating  heat  by  the  lungs.  As  our  bodies  are 
always  producing  much  more  heat  than  is  needed  to 
warm  them,  a  large  proportion  of  this  heat  must  be  given 
out,  in  order  to  keep  the  proper  temperature.  Much  of 
the  extra  heat  passes  off  in  breathing.  If  we  take  in  a 
breath  of  cool  air  and  then  breathe  it  out  close  to  the 
back  of  the  hand,  we  find  that  it  is  much  warmer. 
The  warm  blood  passing  through  the  lungs  has  heated 
the  air,  and  the  blood  is  correspondingly  cooled.  The 
amount  of  heat  which  the  body  loses  in  breathing  differs 
very  greatly  on  different  days.  In  winter  the  cold  air 
may  take  much  heat  from  the  blood  in  the  lungs. 

Sweating  as  a  Means  of  regulating  Heat.  —  In  summer 
the  air  may  be  about  as  warm  as  the  body,  and  in 
this  case  no  heat  at  all  would  be  lost  through  either 
the  lungs  or  the  skin  by  simply  warming  the  air.  In 
hot  weather,  therefore,  another  means  of  getting  rid  of 
the  extra  heat  is  provided.  If  we  wet  a  finger  and 
blow  upon  it  gently,  or  hold  it  in  the  wind,  the  finger 
feels  cool.  The  water  is  evaporated  by  the  wind, 
and  it  takes  a  large  amount  of  heat  to  evaporate  water. 
The  heat  required  to  evaporate  the  water  on  the  finger 
is  taken  from  the  finger  itself,  leaving  this  somewhat 
cooled.  In  the  same  way  the  sweat  that  is  poured  out 
upon  the  skin  is  evaporated,  taking  heat  from  the  body 


KIDNEYS   AND   SKIN   AND   THEIR  DUTIES      169 

and  leaving  this  correspondingly  cooler.  The  more  we 
perspire  the  more  the  evaporation  of  the  sweat  cools  our 
bodies. 

The  sweat  glands  are  connected  with  the  brain 
through  nerves,  and  when  the  body  has  too  much  heat 
a  message  from  the  brain  makes  the  glands  begin  to 
secrete  sweat  profusely.  The  sweat  is  rapidly  evapo- 
rated, and  in  this  way  we  get  rid  of  the  extra  heat  that 
would  make  the  blood  too  hot,  if  there  were  no  way  of 
escape.  The  evaporation  of  the  sweat  takes  so  much 
heat  that  the  body  is  kept  at  its  ordinary  temperature, 
no  matter  how  warm  the  day  may  be. 

Dogs  do  not  sweat  very  much,  and  are  apt  to  suffer 
greatly  from  the  heat  of  summer.  By  their  rapid 
breathing,  or  panting,  they  take  in  large  quantities  of 
air,  which,  passing  through  the  lungs  and  taking  heat 
from  the  blood,  helps  to  keep  down  the  temperature  of 
the  body. 

"  Taking  Cold."  —  There  are  people  who  seem  to  take 
a  certain  pride  in  their  sensitiveness  to  drafts,  and  who 
are  always  ready,  and  expecting,  to  "take  cold."  Such 
persons  usually  do  take  cold  oftener  than  other  people, 
because  they  wrap  their  necks  closely  when  out  of 
doors,  and  in  the  house  they  sit  near  a  register  or  with 
shawls  about  the  shoulders  if  the  air  of  the  room  is  a 
bit  chilly. 

Now  "  taking  cold  "  is  a  habit  which  may  be  almost 
wholly  avoided,  if  we  will  learn  to  treat  the  skin  properly. 
In  the  first  place,  colds  are  not  due  to  exposure  to  cold. 
Explorers  do  not  take  cold  when  in  the  Arctic  regions, 


170  PHYSIOLOGY  AND   HYGIENE 

although  they  may  do  so  after  their  return  home. 
Soldiers  can  sleep  on  the  damp  ground  or  may  be 
out  in  the  rain  for  days  at  a  time  without  catching 
cold.  People  who  live  out  of  doors  seldom  suffer  from 
colds.  We  may  feel  cold  from  such  exposure,  but  we 
do  not  take  cold.  We  know  from  experience  that  we 
can  have  the  face  and  the  hands  exposed  when  the  tem- 
perature is  very  low,  without  catching  cold. 

Yet  it  is  true  that  we  do  sometimes  suffer  this 
disagreeable  malady  if  cold  air  strikes  some  part  of 
the  skin  which  is  usually  protected.  A  slightly  cool 
draft  striking  the  bare  shoulders  may  be  sufficient 
cause.  This  fact  has  given  rise  to  the  idea  that  the 
best  way  to  prevent  taking  cold  is  to  protect  the 
neck  and  shoulders  by  means  of  extra  wraps.  This 
is  a  wrong  method.  If  we  should  cover  our  faces  with 
wraps  in  the  same  way,  they  would  soon  become  so  ten- 
der that  drafts  striking  them  would  produce  colds.  If, 
on  the  other  hand,  we  should  expose  the  neck  as  we  do 
the  face,  it  would  soon  become  so  accustomed  to  changes 
in  temperature  that  it  would  be  as  impervious  to  cold 
as  is  the  face.  It  is,  then,  very  unwise  to  get  into  the 
habit  of  wearing  furs  or  mufflers  around  the  neck,  or  of 
turning  up  the  coat  collar  about  the  ears.  The  extra 
protection  may  be  necessary  for  comfort  on  an  occa- 
sional extremely  cold  day,  but  the  more  we  wrap  the 
neck  the  more  sensitive  it  becomes,  and  consequently 
the  more  liable  we  are  to  take  cold. 


KIDNEYS  AND  SKIN  AND  THEIR  DUTIES      171 


QUESTIONS 

1.  What  are  the  three  waste  products  of  muscle  action  ? 

2.  What  becomes  of  each  of  these  waste  products  ? 

3.  What  are  excretions  and  secretions?    Is  sweat  a  secretion 
or  an  excretion? 

4.  What  organs  produce  secretions? 

5.  Mention  as  many  kinds  of  secretions  as  you  can. 

6.  What  is  the  duty  of  the  kidneys? 
V.   How  are  the  kidneys  constructed  ? 

8.  What  are  the  two  parts  of  the  skin  ? 

9.  Where  is  the  epidermis,  and  what  are  its  characteristics? 

10.  What  are  callosities  and  corns?    Can  callosities  and  blisters 
both  be  produced  by  rubbing  ?    How  ? 

11.  What  are  the  parts  of  a  hair? 

12.  How  should  we  take  care  of  the  hair  ? 

13.  What  are  warts? 

14.  How  do  the  toe  and  finger  nails  grow  ?    Have  the  nails  any 
sensations  ? 

15.  What  is  the  structure  of  the  dermis? 

16.  How  does  the  skin  act  as  a  protection  ? 

17.  What  are  the  sweat  glands? 

18.  How  is  the  heat  lost  through  the  skin  ? 

19.  What  are  cold-blooded  animals? 

20.  If  a  cold-blooded  and  a  warm-blooded  animal  were  placed  in 
an  ice  box,  what  effect  would  be  produced  on  each  ? 

21.  How  is  the  heat  of  the  body  regulated  by  the  lungs  ? 

22.  Why  do  we  need  sweating  to  aid  in  regulating  body  heat? 

23.  How  may  we  avoid  taking  cold? 


CHAPTER  VIII 
THE  CARE  OF  THE  SKIN 

THE  skin,  as  we  have  learned,  is  an  organ  of  great 
importance  to  the  body.  It  is  important  as  a  protect- 
ing organ,  as  an  organ  of  excretion  removing  waste 
products  from  the  body,  and  it  is  at  the  same  time  the 
chief  organ  concerned  in  regulating  the  temperature. 

BATHING 

Cleanliness.  —  In  order  that  the  skin  may  keep  in 
healthy  condition,  it  is  necessary  that  the  sweat  glands 
be  kept  free  and  open.  The  fat  glands  connected  with 
the  hairs  constantly  pour  oil  upon  the  skin,  and  the 
sweat  glands  secrete  considerable  solid  material  with 
the  sweat.  These  substances  remain  upon  the  skin, 
and  unless  they  are  frequently  removed  they  will  in 
time  clog  the  pores,  and  will  also  give  to  a  person  an 
unpleasant  odor  which  renders  him  disagreeable  to 
those  about  him.  Frequent  bathing  and  washing  of 
the  body  is  therefore  desirable.  No  positive  rule  can 
be  given  as  to  the  frequency  with  which  we  should 
bathe.  A  daily  bath  is  advisable,  although  it  is  not 
essential  to  health. 

Cold  Baths.  —  Cleanliness  is  not  the  only  reason  for 
bathing.  The  bath  stimulates  the  skin,  and  this  would 

172 


THE   CARE  OF   THE   SKIN  173 

render  it  of  value  even  if  it  were  not  required  for  pur- 
poses of  cleanliness.  We  have  seen  how  the  delicate 
blood  vessels  expand  and  contract  with  changes  in  tem- 
perature. The  muscle  fibers  of  these  blood  vessels  and 
the  nerves  controlling  them  need  exercise  as  much  as 
do  the  other  muscles  of  the  body.  Our  habits  of  life 
give  them  little  chance  for  this  needed  exercise;  we 
keep  our  rooms  uniformly  warmed,  and  when  we  go 
out  of  doors  on  a  cold  day  we  cover  all  parts  of  the 
body  except  the  face.  Under  these  conditions  the 
blood  vessels  in  the  skin  are  likely  to  become  sluggish, 
and  they  need  stimulation.  The  simplest  way  of  giv- 
ing this  is  by  means  of  the  cold  bath. 

Effects  of  a  Cold  Bath  on  the  Skin.  —  A  cold  bath, 
whether  a  plunge  in  cold  water,  a  shower  bath,  or  merely 
a  sponge  bath,  has  always  with  a  vigorous  person  the 
same  effect.  At  first  there  is  a  sensation  of  cold,  which 
causes  the  blood  vessels  to  contract.  For  a  short  time 
the  skin  may  be  white  and  cold,  but  this  is  presently 
followed  by  what  is  called  the  reaction.  The  blood 
vessels  open  once  more,  allowing  the  warm  blood  from 
the  interior  to  flow  rapidly  through  the  skin.  The 
skin  becomes  flushed  and  warm,  and  there  is  a  feeling 
of  exhilaration,  due  to  this  after  glow. 

A  person  should  leave  the  water  while  still  under 
the  influence  of  the  reaction.  If  he  stays  longer,  he 
becomes  chilly  again,  and  will  remain  cold  and  uncom- 
fortable for  hours.  The  length  of  time  the  after  glow 
lasts  depends  upon  the  person,  the  temperature,  and 
the  water.  It  remains  longer  with  salt  water  than 


174  PHYSIOLOGY  AND   HYGIENE 

with  fresh.  The  greater  the  after  glow,  the  more  bene- 
ficial is  the  bath.  If  the  body  is  rubbed  vigorously 
with  a  rough  towel  after  the  bath,  the  glow  is  much 
increased,  and  the  benefit  correspondingly  greater. 
Indeed,  vigorous  friction  with  a  towel  is  of  fully  as 
much  benefit  as  the  bath  itself. 

The  expansion  and  contraction  of  the  blood  vessels 
thus  brought  about  furnishes  the  skin  with  the  needed 
exercise.  If  a  person  lives  out  of  doors,  exposed  to  all 
sorts  of  weather,  such  exercise  is  not  necessary ;  but  to 
people  spending  most  of  the  time  in  the  house,  such 
a  bath  is  to  the  skin  what  the  gymnasium  is  to  the 
muscles.  A  warm  bath  does  not  accomplish  the  same 
purpose.  It  frequently  makes  one  tired  instead  of 
exhilarated,  and  should  therefore  be  taken  only  after 
the  work  of  the  day  is  done,  instead  of  in  the  morning. 

Sometimes  women  and  young  girls  who  have  not  a 
great  amount  of  vitality  find  that  the  cold  plunge,  or 
even  the  cold  sponge  bath,  fails  to  give  the  desired 
reaction.  In  such  a  case  the  body  should  be  accus- 
tomed to  the  cold  water  gradually.  Little  by  little 
the  space  covered  by  the  cold  water  may  be  extended 
until  the  skin  has  become  sufficiently  toughened  so 
that  the  bath  may  be  made  general.  This  may  usually 
be  accomplished  in  the  course  of  half  a  dozen  mornings. 
To  become  accustomed  to  the  cold  plunge  it  is  best  .to 
begin  with  slightly  warm  water,  using  it  a  little  cooler 
each  day,  until  we  find  we  can  endure  water  which  is 
really  cold.  All  young  persons  will  find  in  the  cold 
bath,  either  plunge  or  sponge,  a  source  of  pleasure 


THE  CARE   OF   THE   SKIN  175 

which,  after  they  have  become  accustomed  to  it,  the 
warm  bath  cannot  give. 

Gold  Baths  a  Protection  against  Colds.  —  This  skin 
exercise  renders  the  cold  bath  a  protection  against 
colds.  If  we  will  accustom  ourselves  to  a  cold  sponge 
bath  every  morning,  and  will  avoid  covering  the  neck 
with  thick  wraps,  we  are  much  more  likely  to  escape 
the  habit  of  taking  cold.  The  person  who,  by  means  of 
heavy  wraps,  protects  his  skin  from  exposure,  and  who 
takes  only  warm  baths,  is  pretty  sure  to  get  into  a  con- 
dition that  favors  taking  cold.  He  then  regrets  that 
he  "takes  cold  so  easily."  The  remedy  may  be  in  his 
own  hands.  It  consists  in  adopting  a  mode  of  life  that 
will  give  his  skin  the  needed  exercise. 

Hot  Baths.  —  We  can  easily  test  the  difference  in 
effect  of  the  cold  and  the  hot  bath.  If  we  bare  the 
arm  and  pour  cold  water  upon  it,  then  rub  it  briskly, 
the  skin  becomes  red  and  warm  with  the  after  glow. 
If  we  plunge  the  arm  into  water  as  hot  as  can  comfort- 
ably be  borne  it  first  grows  red,  then  turns  white,  and 
there  is  no  after  glow.  There  are  times,  however,  when 
a  hot  bath  is  beneficial.  It  may  enable  one  who  is  rest- 
less and  wakeful  to  go  to  sleep,  since  it  draws  the 
blood  from  the  brain.  When  we  feel  a  cold  coming 
on,  a  hot  bath  or  even  soaking  the  feet  in  hot  water 
may  draw  the  blood  from  the  throat  and  nose  suffi- 
ciently to  prevent  the  cold  from  developing.  An  occa- 
sional hot  bath  is  also  desirable  for  the  cleansing  of  the 
body,  even  though  cold  baths  are  frequently  taken. 


176  PHYSIOLOGY  AND   HYGIENE 

CLOTHING 

We  should  remember  that  we  wear  clothing  for  the 
purpose  of  comfort  or  adornment  rather  than  to  protect 
us  from  taking  cold.  For  comfort  it  is  necessary,  in 
cold  weather,  to  cover  the  body  very  completely  with 
clothing.  We  should  remember,  however,  that  the 
clothing  does  not  warm  the  body,  but  simply  holds  in 
our  body  heat,  keeping  it  from  passing  off  by  way  of 
the  skin.  Any  clothing  that  conducts  or  sends  off  heat 
rapidly  will  cool  the  body  quickly.  Clothing  that  con- 
ducts heat  slowly  will  keep  the  body  warm.  Linen  and 
cotton  carry  the  heat  away  rapidly,  while  woolen  cloth- 
ing holds  it  back.  We  should  therefore  wear  linen  or 
cotton  garments  in  the  summer  time,  and  woolen  cloth- 
ing in  the  winter.  Coarsely  woven  cloth,  which  is  filled 
with  air  spaces,  carries  the  heat  away  very  slowly. 
Clothing  made  of  such  material  is,  then,  the  very  best 
for  keeping  the  body  warm  in  cold  weather.  Similarly, 
two  light  garments,  worn  one  over  the  other,  are  warmer 
than  one  heavy  one  of  equal  weight.  The  air  space 
between  the  two  acts  as  a  "non-conductor"  of  heat. 

When  we  sleep,  our  bodies  should  be  more  warmly 
covered  than  when  we  are  awake.  A  good  rule  to  keep 
in  mind  is  that  for  sleeping  the  feet  should  be  warm 
and  the  head  cool.  As  the  body,  during  sleep,  needs 
rest  as  much  as  possible,  it  ought  not  to  be  compelled  to 
keep  up  any  extra  amount  of  heat.  Paper  is  a  material 
which  readily  holds  back  heat,  and  if  a  couple  of  news- 
papers be  placed  between  two  pieces  of  bed  clothing 


THE   CARE   OF   THE   SKIN  177 

they  do  as  good  service  in  keeping  the  body  warm  as 
a  blanket. 

BURNS 

Burns  are  very  common  injuries  to  the  skin  and  are 
often  very  serious.  In  case  of  a  slight  burn  we  can 
usually  relieve  the  pain  for  a  time  with  cold  water. 
One  of  the  best  applications  for  a  burn  is  a  paste  which 
can  be  quickly  made  by  rubbing  soda  or  baking  powder 
into  some  vaseline  or  sweet  oil.  Place  this  paste,  which 
should  be  thin  enough  to  spread  easily,  on  a  clean  cloth 
and  apply  it  so  that  it  shall  completely  cover  the  burn. 
Another  method  is  to  apply  a  cloth  wet  in  a  solution  of 
baking  powder  or  saleratus  and  water.  This  solution 
is,  however,  less  soothing  than  the  paste,  and  the  cloth 
must  be  soaked  in  it  frequently.  The  burn  should 
always  be  protected  from  the  air.  This  may  be  done 
in  an  emergency  by  applying  linseed  oil,  lime  water,  or 
even^owr,  to  the  place,  but  no  cotton  wadding  should 
be  put  on  the  wound  or  anything  else  that  might  leave 
little  particles  on  the  surface.  If  the  burn  is  neither 
very  deep  nor  very  extensive,  it  will  heal  readily;  but 
if  it  is  severe,  it  should  be  cared  for  by  a  physician. 

Life  might  sometimes  be  saved  if  people  would  re- 
member what  to  do  in  case  the  clothing  catches  fire. 
If  the  clothing  gets  afire,  one  should  catch  up  any 
woolen  article  that  may  be  at  hand,  wrap  it  closely 
around- the  burning  clothing,  and  immediately  lie  down 
flat  upon  the  floor  or  the  ground,  and  roll  over  and  over 
Without  air  the  fire  cannot  burn,  and  the  rapid  rolling, 


178  PHYSIOLOGY  AND   HYGIENE 

even  if  one  cannot  reach  any  woolen  stuff  to  serve  as  an 
extinguisher,  will  usually  put  out  the  fire.  People 
have  lost  their  lives  by  standing  up  while  attempting 
to  remove  burning  clothes.  The  flames  rise,  and  if 
the  person  is  standing,  he  is  very  liable  to  breathe  the 
fire  into  his  lungs.  This  causes  almost  instant  death. 
If  a  person  whose  clothing  is  on  fire  loses  his  wits 
and  starts  to  run,  he  should  be  thrown  down  as  a  means 
of  saving  his  life,  for  running  is  very  dangerous.  He 
should  then  be  wrapped  in  a  rug,  a  blanket,  a  coat,  or 
any  similar  heavy  article  that  may  be  at  hand,  to 
smother  the  flames.  After  the  fire  is  out,  if  the  flesh 
of  the  person  is  burned,  the  clothing  must  be  removed. 
Care  must  be  taken,  however,  that  the  skin  is  not  torn 
off.  The  clothing  is  likely  to  stick  to  the  skin,  and  if 
it  does  so,  it  should  be  allowed  to  remain,  at  least  where 
it  adheres,  the  cloth  being  cut  off  around  the  place  if 
necessary.  If  there  are  blisters,  they  should  be  opened 
and  the  liquid  pressed  out.  Any  further  treatment 
should  be  given  by  a  physician. 

FROSTBITES 

The  freezing  of  fingers,  toes,  nose,  or  ears  is  not  an 
uncommon  occurrence  on  an  extremely  cold  day.  In 
such  a  case,  the  water  in  the  blood  and  the  muscles  is 
actually  turned  to  ice.  If  the  frozen  parts  are  thawed 
out  slowly,  no  permanent  injury  may  result ;  but  if 
they  are  thawed  rapidly,  serious  trouble  may  follow, 
which  may  render  amputation  of  the  toes  or  fingers 
necessary.  For  this  reason  frostbites  should  be  thawed 


THE  CARE  OF   THE   SKIN  179 

slowly.  Rubbing  the  frozen  parts  with  snow  or  cold 
water  is  recommended.  This  will  thaw  them  out  with 
the  least  possible  danger  of  injury.  In  general,  to 
preserve  a  part  of  the  body  that  has  been  frozen,  it 
must  be  promptly  but  very  gradually  thawed.  After 
this  the  person  may  be  warmed  and  given  some  warm 
drink,  such  as  hot  water,  milk,  or  coffee. 

Many  people  wrongly  suppose  that  the  uncomfort- 
able affection  of  the  feet  known  as  "  chilblains  "  is  the 
result  of  frostbite.  They  are  really  due  to  getting 
the  feet  very  cold  and  then  warming  them  too  quickly, 
and  do  not  appear  in  children  with  a  vigorous  circu- 
lation. Warming  cold  feet  over  a  register  or  in  a 
stove  oven  is  very  likely  to  cause  the  difficulty.  The 
best  way  to  protect  the  feet  against  chilblains  is  to  wear 
warm  stockings  and  thick  shoes  in  cold  weather,  and 
give  the  feet  plenty  of  exercise. 

QUESTIONS 

1.  Why  should  the  sweat  glands  be  kept  free  and  open? 

2.  What  is  the  use  of  sweat  ? 

3.  What  is  the  effect  of  the  cold  bath? 

4.  What  are  the  advantages  of  the  cold  bath  ? 

5.  How  do  cold  baths  act  as  a  protection  against  colds  ? 

6.  What  is  the  difference  in  effect  between  the  cold  and  the 
hot  bath  ? 

7.  What  clothing  is  most  suitable  for  summer?    For  winter? 

8.  Are  silk  underclothing  and  stockings  as  useful  as  woolen? 
Why? 

9.  Why  should  the  body  be  warmly  covered  during  sleep  ? 

10.  What  should  be  done  when  a  person's  clothing  catches  fire? 

11.  What  should  be  done  for  frostbite  ? 


CHAPTER  IX 
ALCOHOL  AND  OTHER  NARCOTICS 

MANY  people  have  the  habit  of  using  certain  sub- 
stances which  interfere  with  the  health  of  various  parts 
of  the  body.  These  substances  are  chiefly  alcohol  and 
narcotics. 

Alcohol  is  sometimes  incorrectly  called  a  stimulant. 
A  true  stimulant  is  some  agent  that  increases  the 
activity  of  some  organ.  For  example,  hot  water  stimu- 
lates heart  action  ;  chewing  rubber  stimulates  the  secre- 
tion of  saliva.  Sometimes  the  term  is  wrongly  used  to 
apply  to  the  action  of  some  poison  like  strychnine  that 
makes  the  body  very  excitable  but  really  decreases 
instead  of  increasing  its  efficiency. 

Narcotics  have  just  the  opposite  effect.  They  soothe 
and  dull  the  action  of  the  body  and  have  a  tendency  to 
put  people  to  sleep.  Although  narcotics  and  stimu- 
lants are  thus  very  different,  they  are  sometimes  con- 
fused, since  the  same  drug  may  seem  to  possess  both 
effects.  Alcohol,  for  example,  is  a  narcotic.  But  its 
first  action  is  to  dull  the  powers  of  self-restraint  in  the 
brain,  and  this  causes  the  person  to  do  and  say  things 
that  give  the  false  impression  of  extra  strength.  For 
this  reason  it  has  been  wrongly  called  a  stimulant.  As 
its  action  increases,  however,  its  dulling  effect  becomes 
more  evident  and  is  more  lasting.  Its  true  action  is, 
therefore,  that  of  a  narcotic  and  not  that  of  a  stimulant. 
When  a  larger  quantity  is  taken,  the  narcotic  effect  is 
unmistakable. 

180 


ALCOHOL  AND  OTHER  NARCOTICS  181 

OPIUM 

Opium  is  one  of  the  most  dangerous  of  narcotics. 
Morphine  and  laudanum  are  two  common  forms  of  the 
drug.  Paregoric  and  soothing  sirup,  both  of  which 
contain  opium,  are  especially  dangerous,  and  should 
not  be  given  to  children.  Opium  dulls  the  senses  and 
finally  puts  a  person  to  sleep.  The  reason  why  it 
is  so  dangerous  is  that  it  has  a  tendency  to  produce 
a  terrible  craving  for  opium. 

A  person  begins  by  taking  a  small  amount,  possibly 
prescribed  for  him  by  a  physician  as  a  remedy  for 
toothache,  headache,  or  neuralgia.  The  drug  not  only 
soothes  the  pain,  but  produces  a  pleasant,  restful  feel- 
ing. Whenever  the  person  has  a  pain  which  he  wishes 
to  relieve,  he  uses  the  same  remedy,  or  he  even  imagines 
the  pain  for  the  sake  of  taking  the  drug.  Soon  the 
small  doses  with  which  he  began  cease  to  produce  the 
desired  effect,  and  he  takes  larger  amounts.  Before 
he  suspects  the  fact,  he  has  become  an  "  opium  eater," 
and  no  longer  even  pretends  to  make  the  excuse  that 
he  takes  the  drug  as  a  medicine. 

Opium  destroys  the  ability  to  think  clearly  and  ruins 
the  moral  nature.  The  opium  eater  frequently  becomes 
a  liar  and  a  thief.  His  health  is  undermined.  He  no 
longer  finds  pleasure  in  work  or  in  recreation,  and  after 
a  while  even  the  drug  itself  ceases  to  give  him  relief  or 
satisfaction.  The  use  of  the  drug  so  affects  his  will 
power  that  when  he  finds  himself  a  slave  to  the  habit 
he  has  not  the  strength  of  will  to  restrain  the  appetite. 


182  PHYSIOLOGY  AND  HYGIENE 

When  once  the  terrible  habit  has  obtained  a  hold  upon 
a  man,  it  is  almost  impossible  for  him  to  control  it. 
The  use  of  opium  in  any  form,  except  under  the  direct 
advice  of  a  physician,  is  consequently  exceedingly 
dangerous.  Many  physicians  are  unwilling  to  pre- 
scribe it,  knowing  as  they  do  how  easily  the  habit  is 
formed. 

The  use  of  Moral  and  cocaine  is  equally  dangerous, 
the  effects  being  similar  to  those  of  opium. 

TOBACCO 

Tobacco  is  a  milder  narcotic  than  opium,  and  one 
much  more  widely  used.  Tobacco  contains  a  poison 
which  is  deadly  when  taken  in  considerable  quantity. 
Whether  or  not  the  amount  of  this  poison  taken  into 
the  body  by  a  grown  person  who  smokes  but  little  is 
enough  to  produce  injury,  there  is  no  question  about 
the  ill  effects  of  tobacco  on  young  people,  however 
moderately  it  may  be  used.  Used  freely,  it  is  un- 
doubtedly injurious  to  adults. 

Moreover,  mild  narcotics  like  tobacco  share  with  the 
stronger  narcotics,  though  in  less  degree,  that  power  of 
making  the  user  want  more  and  more  of  them.  There 
are  many  other  excellent  reasons  for  refraining  from 
the  habit  of  using  tobacco. 

1.  Tobacco  is  of  absolutely  no  value  to  the  healthy 
body.     It  neither  acts  as  a  food  nor  does  it  serve  any 
other  useful  purpose. 

2.  The  use  of  tobacco  by  young  people  may  check  the 


ALCOHOL   AND  OTHER  NARCOTICS  183 

proper  growth  and  development  of  the  body.  Careful 
study  of  college  students  has  shown  that  those  who  are 
addicted  to  the  use  of  tobacco  are,  on  the  average,  con- 
siderably less  developed  than  those  who  let  it  alone. 
The  tobacco  habit  handicaps  a  boy  in  his  physical 
development  at  the '  very  start  of  life. 

3.  The    use   of    tobacco    temporarily   reduces   one's 
muscular  power,  and  may  do  so  permanently. 

4.  Its  use  often  causes  heart  trouble.  The  "  cigarette 
heart "  is  well  known  to  physicians.     Brain  difficulty, 
insanity,  and  even  death  are  sometimes  traceable  to 
tobacco. 

5.  It  is  an  expensive  habit.     The  money  spent  for 
tobacco  could  certainly  be  put  to  better  use,  and  could 
be  employed  in  ways  that,  to  a  young  person  at  least, 
would  give  more  pleasure  and  profit. 

6.  It  is   a  habit   that    renders    one    disagreeable  to 
others  and  tends  to  selfishness.     Most  people  who  do 
not  use  tobacco,  women  especially,  find  the  use  of  it 
by   their    acquaintances   very   disagreeable.      Its   use 
sometimes  tends  to  selfishness  and  to  a  disregard  of 
the  feelings  of  others. 

7.  The  use  of  tobacco  is  likely  to  lead  boys  into  inju- 
rious company,  inviting  them  to  idleness  and  to  other 
bad  habits. 

Of  all  forms  of  tobacco,  cigarettes  probably  do  the 
greatest  amount  of  injury.  A  person  who  uses  cig- 
arettes is  likely  to  "  inhale  "  the  smoke.  This  means 
breathing  the  smoke  into  the  lungs,  which  is  far  more 
injurious  than  simply  taking  it  into  the  mouth.  Boys 


184  PHYSIOLOGY  AND   HYGIENE 

in  particular  should  know  this,  for  cigarettes  are  gener- 
ally used  by  them  on  account  of  their  cheapness. 

For  these  reasons  the  wise  course  is  to  leave  tobacco 
alone. 

ALCOHOL 

One  of  the  greatest  dangers  that  a  young  person 
has  to  meet  is  that  of  acquiring  the  alcohol  habit. 
Fortunately,  it  is  not  so  common  as  the  tobacco  habit. 
Nevertheless,  it  has  destroyed  the  lives  of  hundreds  of 
thousands  of  young  people,  and  has  been  a  stumbling 
block  in  the  way  of  hundreds  of  thousands  of  others. 
It  has  led  to  countless  crimes,  and  has  caused  an  ines- 
timable amount  of  poverty  and  suffering.  The  use  of 
alcohol  is  particularly  dangerous,  because  it  frequently 
obtains  a  mastery  over  young  people  without  their  real- 
izing the  fact. 

Use  of  Alcohol  in  Large  Quantities.  —  The  effect  of 
alcohol  upon  the  body  depends  largely  upon  the  amount 
used.  When  speaking  of  the  use  of  alcohol  in  large 
quantities,  people  mean  its  use  in  quantities  sufficient  to 
produce  intoxication,  or  with  a  frequency  that  keeps  the 
person  more  or  less  under  its  influence.  The  use  of 
alcohol  in  such  quantities  is  disastrous  to  health.  It  in- 
jures the  action  of  the  heart,  interferes  with  circulation, 
and  impairs  the  digestive  powers.  Moreover,  it  has  a 
very  important  influence  upon  the  moral  nature.  The 
drunkard  loses  his  sense  of  responsibility  and  ceases 
to  be  a  normal  man.  His  whole  body  becomes  dis- 
eased and  unable  to  carry  on  its  proper  functions.  His 


ALCOHOL  AND  OTHER  NARCOTICS  185 

mind  becomes  dull  and  his  ambitions  disappear.  The 
use  of  alcohol  in  large  quantities  destroys  a  man's 
chance  of  the  highest  success.  Alcohol  causes  the 
death  of  thousands  of  men  and  women  every  year. 

Use  of  Alcohol  in  Smaller  Quantities.  —  When  alco- 
holic drinks  are  used  in  quantities  insufficient  to  pro- 
duce intoxication,  their  effect  upon  the  body  may  also 
be  serious,  although  unfortunately  not  always  apparent. 
The  injury  is  so  gradual  that  there  may  be  little  to  call 
attention  to  it.  Some  people  use  wines  or  beers  in 
small  amounts  for  years  without  realizing  that  they  are 
injured  by  them;  nevertheless,  alcoholic  drinks,  when 
habitually  used,  even  in  small  quantities,  frequently 
produce  decidedly  injurious  effects.  There  is  always 
the  danger  of  forming  the  craving  for  more. 

The  effect  of  using  alcohol  in  small  quantities  does 
not  appear  at  once.  Its  action  when  so  used  was 
shown  recently  by  a  series  of  experiments  upon  dogs, 
made  by  Dr.  Hodge,  of  Clark  University.  Four 
dogs  were  selected  from  the  same  litter,  all  as  nearly 
alike  as  possible.  Two  of  them  were  given  only  ordi- 
nary food.  The  other  two  were  treated  in  exactly  the 
same  way,  except  that  they  were  given  a  small  amount 
of  alcohol  with  each  meal.  They  were  never  given 
alcohol  enough  to  make  them  intoxicated,  and,  taking 
into  consideration  the  relative  size  of  the  dogs  and 
a  man,  the  amount  given  was  relatively  about  as 
much  as  would  be  taken  by  many  moderate  drinkers. 
At  first  the  four  dogs  were  practically  alike,  but  little 
by  little  differences  began  to  appear  between  those  that 


186  PHYSIOLOGY  AND  HYGIENE 

were  given  the  alcohol  and  those  that  had  nothing  but 
the  regular  food. 

In  the  course  of  a  few  months  the  "alcohol"  dogs  were 
quite  inferior  in  appearance  to  the  other  two.  By  the 
end  of  a  year  and  a  half  the  difference  was  very  marked. 
The  "alcohol"  dogs  were  sleepy,  and  had  a  general  ap- 
pearance of  worthlessness.  They  were  less  active  than 
the  other  dogs,  and  were  much  more  quickly  tired  out. 
They  would  not  bring  back  a  ball  when  it  was  thrown 
for  them  so  often  as  the  others,  and  they  frequently 
lay  down  to  rest.  In  other  words,  the  use  of  alcohol 
had  lowered  the  intelligence,  the  brightness,  and  the 
muscular  power  of  the  dogs. 

If  a  moderate  use  of  alcohol  affects  dogs  so  much 
in  eighteen  months,  we  may  be  sure  that  it  has  some 
injurious  effect  on  the  people  who  continue  its  use  in 
this  way  for  years.  Whatever  success  in  life  has  been 
made  by  a  man  who  is  a  moderate  drinker,  he  would 
certainly  have  amounted  to  as  much  without  the  alco- 
hol, and  perhaps  a  great  deal  more. 

Competition  is  so  great  in  these  days,  in  business,  in 
the  professions,  and,  in  fact,  along  every  possible  line  of 
work,  that  the  boy  or  young  man  of  the  present  day 
needs  to  have  every  possible  power  of  mind  and  body 
at  his  command.  The  man  with  clear  and  unimpaired 
brain,  with  a  healthy,  well-cared-for  body,  with  body 
and  brain  controlled  by  a  determined,  resolute  will  — 
he  is  the  man  who  will  make  a  success  in  the  coming 
years  of  the  twentieth  century. 

The  Alcohol  Appetite. — We  have  already  learned  that 


ALCOHOL   AND  OTHER  NARCOTICS  187 

one  of  the  most  dangerous  things  about  alcohol  is  its 
tendency  to  create  a  desire  for  more.  This  desire  may 
be  very  slight  at  first,  but  it  is  likely  to  grow.  More- 
over, although  at  first  a  small  amount  of  alcohol  is  all 
that  a  person  wants,  or  can  drink,  when  his  body  be- 
comes accustomed  to  this  amount,  he  almost  without 
knowing  it  takes  a  little  more.  Quite  unconscious  of 
how  serious  a  thing  it  is,  he  slowly  increases  the  amount 
used,  sometimes  by  taking  a  larger  amount  of  weak 
liquors  and  sometimes  by  taking  stronger  ones.  He 
begins  with  beer  and  finally  uses  distilled  liquors.  The 
appetite  grows  with  indulgence,  and  sooner  or  later 
it  may  become  so  firmly  fixed  that  he  is  quite  unable 
to  break  it. 

Danger  of  the  Appetite.  —  The  fact  that  the  appetite 
grows  slowly  and  imperceptibly  is  what  makes  alcohol 
so  dangerous.  If  a  boy  or  young  man  could  appreciate 
how  the  appetite  is  increasing,  if  he  could  realize  to 
what  it  is  likely  to  lead  him,  and  if  he  could  under- 
stand at  the  beginning  how  he  is  slowly  becoming  bound 
by  a  habit,  he  would  in  most  cases  curb  the  habit  before 
it  developed  much  strength.  But  the  habit  grows  im- 
perceptibly, and  at  the  same  time  undermines  his  will, 
until  it  finally  produces  disastrous  results. 

The  continued  use  of  alcohol,  moreover,  is  likely  to 
crush  out  all  desire  to  reform.  The  alcohol  appetite 
might  be  overcome  in  most  cases  if  the  person  had  a 
sufficiently  strong  desire  to  do  so ;  but  his  will  power 
and  his  desire  for  a  better  life  are  taken  away  as  the 
appetite  grows  upon  him. 


188  PHYSIOLOGY  AND   HYGIENE 

It  is  undoubtedly  true  that  thousands  of  people  who 
begin  to  use  alcohol  in  small  quantities,  develop  the 
alcohol  appetite  and  are  finally  mastered  by  it.  Every 
boy  who  begins  to  drink  runs  the  danger  of  developing 
such  an  appetite.  He  may  not  become  mastered  by  it, 
but  experience  has  shown  that  in  many  cases  the  boy 
finds  himself  in  time  mastered  by  the  habit.  It  is  never 
possible  to  predict  what  will  be  the  result.  Drunkards 
are  commonly  made  out  of  boys  and  girls  who  do  not 
intend  to  use  enough  alcohol  to  injure  them.  If  a  boy 
never  begins  to  use  alcoholic  liquors,  he  will  never  be- 
come a  drunkard  ;  but  if  he  does  begin,  even  in  a  mild 
way,  he  places  himself  among  those  from  whom  drunk- 
ards are  made.  The  only  sure  way  to  avoid  this  danger 
is  to  avoid  its  beginning,  and,  in  avoiding  that,  the  boy 
also  insures  for  himself  a  healthier  body,  a  clearer  brain, 
and  a  better  chance  for  success  in  life. 

QUESTIONS 

1.  What  is  the  difference  between  a  stimulant  and  a  narcotic  ? 

2.  What  is  the  effect  of  opium,  and  why  is  it  a  dangerous 
drug? 

3.  Why  should  tobacco  not  be  used? 

4.  What  is  the  effect  upon  the  body  of  using  alcohol  in  large 
quantities  ? 

5.  What  are  the  effects  of  a  moderate  use  of  alcohol  ? 

6.  What  do  you  regard  as  the  strongest  reason  for  avoiding 
alcoholic  drinks  ? 


CHAPTER  X 
THE   NERVOUS  SYSTEM 

EVERY  large  factory  must  have  a  superintendent. 
Otherwise  the  persons  employed  to  do  various  tasks 
would  work  independently  of  one  another,  and  as  a 
result  little  would  be  accomplished.  The  superin- 
tendent is  indeed  the  most  important  man  in  the 
entire  factory. 

Within  our  bodies  various  actions  are  going  on. 
About  five  hundred  muscles,  numerous  glands,  and  many 
other  organs  are  constantly  at  work.  If  they  should 
act  independently  there  would  be  great  confusion.  In 
our  bodies,  however,  as  in  the  factory,  there  is  a  super- 
intendent, whose  duty  it  is  to  control  all  the  different 
parts  and  keep  them  working  in  harmony  with  each 
other.  A  few  of  the  body  actions,  like  the  beating  of 
the  heart,  can  take  place  without  direct  command  from 
the  superintendent,  but  with  the  others  the  order  of 
the  superintendent  is  required  before  the  organs  will 
work  at  all. 

The  muscles  will  never  act  unless  they  are  com- 
manded  to  do  so  by  the  central  controlling  organ.  As 
we  have  already  learned,  the  organ  that  corresponds 
in  the  body  to  the  superintendent  of  a  factory,  and 
that  controls  the  numerous  activities,  is  the  brain. 

189 


190 


PHYSIOLOGY  AND   HYGIENE 


The  brain  is  connected  with  every  part  of  the  body 
by  a  series  of  nerves.  This  is  the  organ  with  which 
we  think,  and  by  means  of  which  we  will  to  do  any- 
thing. The  brain  also  causes  a  great  many  actions  to 
take  place  in  our  bodies  without  any  knowledge  on 
our  part.  We  do  not  realize,  for  instance,  that  mes- 
sages are  being  sent  from  the  brain  to  the  blood  vessels 
of  the  skin,  causing  them  to  open  or  shut. 


THE  BRAIN 

The  brain  fills  the  bony  box  called  the  skull.    Figure 
65  shows  its  shape  and  structure.     It  is  a  very  large 


FIG.  65.  —  THE  HUMAN  BRAIN. 


organ,  that  of  an  adult  weighing  some  three  pounds. 
There  is  considerable  difference  in  the  weight  of  vari- 
ous brains.  The  more  intelligent  races  commonly  have 
large  brains,  while  those  of  less  intelligence  usually 


THE  NERVOUS  SYSTEM  191 

have  smaller  ones.  There  are,  however,  among  individ- 
uals, some  remarkable  exceptions  to  this  general  rule. 
The  brain  is  a  very  complicated  organ.  As  shown  in 
Figure  65,  it  is  divided  into  three  main  parts,  each  of 
which  has  special  duties  to  perform. 

The  Medulla  Oblongata.  —  Forming  the  very  lowest 
part  of  the  brain  is  the  medulla,  or  medulla  oblongata, 
which  lies  between  the  spinal  cord  and  the  main  part 
of  the  brain.  It  is  not  more  than  one  and  a  quarter 
inches  in  length,  yet  it  contains  the  centers  that  control 
some  most  important  body  actions.  As  Figure  65  indi- 
cates, the  breathing,  the  vasomotor  system  (i.e.  expan- 
sion and  contraction  of  blood  vessels),  the  heart  control, 
and  swallowing,  together  with  other  functions,  are  the 
special  care  of  this  part  of  the  brain. 

The  Cerebellum.  —  A  little  higher  than  the  medulla 
is  situated  a  larger  rounded  part  of  the  brain,  about 
half  as  large  as  a  baseball,  called  the  cerebellum.  It 
is  somewhat  flattened  and,  as  Figure  65  indicates,  is 
marked  with  numerous  furrows.  It  lies  over  the 
medulla.  The  cerebellum  is  thought  to  influence  mus- 
cular action.  We  have  seen  how  wonderfully  the 
muscles  are  adjusted  so  as  to  act  together,  as,  for 
instance,  when  a  boy  throws  a  stone.  This  is  sup- 
posed to  be  accomplished  in  part  through  the  action 
of  the  cerebellum. 

The  Cerebrum.  —  The  cerebrum  is  the  largest  part  of 
the  brain.  Figure  65  shows  that  it  is  covered  with 
deep  furrows  which  divide  it  into  folds  called  convo- 
lutions. These  folds  are  not  exactly  alike  in  all  brains, 


192 


PHYSIOLOGY  AND  HYGIENE 


though  the  larger  ones  are  almost  always  present.    The 
cerebrum  is  divided  by  a  very  deep  furrow  into  two 

parts,  called  the  right  and  the 
left  hemispheres.  The  division 
is  indicated  in  Figure  66.  The 
two  parts  are  connected  with 
the  body  in  such  a  way  that  the 
right  hemisphere  controls  the 
left  side  of  the  body,  and  the 
left  hemisphere  the  right  side 
of  the  body.  The  cerebrum 
is  the  part  of  the  brain  that 
is  active  in  thought  and  in  the 
exercise  of  will  power.  What 
we  call  the  "  mind  "  is  centered 
in  the  cerebrum.  It  is  the 
center  which  starts  and  con- 
trols the  activity  of  the  body. 


THE  SPINAL   CORD 


FIG.  66.  —  THE  NERVOUS 

SYSTEM. 

Showing  the   brain  and  the        A    long,    soft,    white     cord, 
spinal  cord  with  its  nerves.      called    ^    spinal   ^    starts 

from  the  lower  end  of  the  medulla  (shown  in  Fig.  66), 
and  passes  down  through  the  backbone  or  spine.  The 
vertebrae  of  the  backbone  protect  the  cord  on  all  sides. 
In  other  words,  the  spinal  cord  runs  inside  the  back- 
bone (see  Fig.  43,  p.  126).  As  may  be  seen  from  Fig- 
ure 66,  the  cord  is  not  of  the  same  thickness  throughout 
its  length,  but  it  becomes  gradually  smaller  as  it  passes 
down  the  back.  At  the  lower  end  it  divides  into  fine 


THE  NERVOUS  SYSTEM 


193 


threads.  When  in  its  proper  position  inside  the  back- 
bone, the  cord  is  covered  not  simply  with  bones,  but 
with  certain  softer  membranes,  which  act  as  a  further 
protection,  so  that  it  is  very  thoroughly  guarded  from 
injury. 

If  we  cut  the  cord  directly  across,  it  will  appear  as 
we  see  it  in  Figure  67.    Like  the  brain,  it  is  divided  by 
deep  furrows  into 
two      parts,       the 
right  half  and  the 
left  half.    The  fur- 
rows, as  the  figure 
shows,  do  not  ex- 


AnteriorRoot 


tend   all    the   way 
across     the     cord, 


FIG.  67.  —  Two  PIECES  OF  THE  SPINAL 
CORD. 

Showing  the  gray  matter  and  the  two  roots 
of  the  spinal  nerves.  The  arrows  show 
the  direction  of  the  stimuli. 


but  the  two  halves 
are  united  at  their 
center.  At  the 

very  center  of  the  cord,  Figure  67  shows  a  rather  irreg- 
ular mass,  shaped  somewhat  like  the  letter  H,  with  four 
arms  running  off  to  the  sides.  This  material  is  of  a 
dull  gray  color,  and  is  called  the  gray  matter.  It  con- 
tains nerve  cells,  which  start  and  receive  nervous  im- 
pulses, or  "messages."  Outside  the  gray  matter  is 
a  substance,  whiter  and  more  glistening,  called  the 
white  matter  of  the  cord.  This  consists  of  nerve 
fibers,  whose  duty  it  is  to  carry  up  and  down  the  cord 
the  nervous  impulses  which  are  started  and  received  by 
the  gray  matter. 


194  PHYSIOLOGY  AND  HYGIENE 

THE  NERVES 

The  brain  may  be  regarded  as  the  superintendent  of 
the  body.  If  this  superintendent  is  to  have  any  control 
over  the  different  organs  in  the  body,  it  must  in  some 
way  be  connected  with  them.  The  superintendent  of 
a  factory  often  has  telephone  connection  with  every 
room  in  the  building  by  means  of  electric  wires  which 
run  in  various  directions.  In  a  similar  way  the  super- 
intendent of  our  body,  the  brain,  is  connected  with 
every  part  of  the  body  by  a  series  of  connecting  fibers 
which  we  call  nerves. 

Figure  66  shows  these  nerves  coming  from  the  spinal 
cord  as  it  passes  down  through  the  back.  The  nerves 
start  in  the  gray  matter  of  the  cord,  and  then  pass  from 
the  cord  between  the  vertebrae,  extending  outward  into 
the  body  to  connect  with  all  the  organs  controlled  by  the 
brain.  As  may  be  seen  from  Figure  67,  each  of  these 
nerves  rises  from  the  cord  in  two  branches,  known  as 
roots.  The  front  branch,  called  the  anterior  root,  carries 
nervous  impulses  from  the  brain  to  the  muscles;  while 
the  other,  the  posterior  root,  carries  nervous  impulses 
from  the  skin  and  other  organs  to  the  spinal  cord  and 
thence  to  the  brain. 

After  the  two  branches  unite,  as  shown  in  the  figure, 
they  form  what  we  call  a  nerve  trunk.  Such  a  trunk 
is  made  up  of  thousands  of  nerve  fibers,  or  wires,  bound 
together  in  a  bundle.  Each  fiber  runs  to  a  distinct 
part  of  the  body.  Figure  68  shows  a  bundle  of  fibers 
that  make  up  a  nerve.  A  nerve  trunk  usually  con- 


THE  NERVOUS  SYSTEM 


195 


Meduh 


tains  some  fibers  that  carry  impulses  toward  the  brain 
and  some  that  carry  them  away  from  it.  A  few 
nerves,  however,  contain  only  one  kind  of  fiber.  By 
means  of  these  hundreds  of  thousands  of  nerve  fibers 
every  muscle,  every  gland,  every 
part  of  the  skin,  receives  and 
sends  nervous  impulses  to  and 
from  the  brain. 

The  wire  that  rings  an  electric 
bell  is  always  connected  with  two 
different  pieces  of  apparatus,  with- 
out which  it  would  be  useless.  At 
one  end  of  the  wire  is  placed  the 
bell  to  be  rung ;  at  the  other  end 
there  is  a  battery,  which  starts  the 
electric  current  that  rings  the  bell. 
The  wire  serves  simply  to  connect  fylinder— ] 

the  battery  with   the  bell.      The 

J  Single. 

nerves   in   our   body   serve,  in  a       Nerve 

similar  way,  to  connect  two  pieces      j£*J£_A  NERVE> 
of  apparatus  placed  at  their  ends,    Showing  on  the  right'a 
corresponding  to  the  battery  and       nerve    composed    of 

the  bell.  the  raany  nerve  fibers 

and  on  the  left  a  single 

If  we  could  examine  carefully       nerve  fiber, 
the  nerve  fibers,   we  should  find 

that  many  of  them  end  in  a  minute,  somewhat  rounded 
body,  with  numerous  branches  extending  from  it  on 
all  sides  (Fig.  69).  This  body  is  called  a  nerve 
cell  and  it  corresponds  in  its  work  to  the  battery 
that  starts  the  electric  impulse  to  ring  the  bell.  Since 


196 


PHYSIOLOGY  AND  HYGIENE 


the  nerve  cells  are  the  organs  that  start  and  receive 
nervous  impulses,  we  should  expect  to  find  them  most 
numerous  where  stimuli  are  sent  out  to  the  various 
organs ;  and  this  is  the  case.  There  are  a  great  many 

nerve  cells  in  the  spinal  cord, 
and  in  the  brain  they  are  so 
numerous  that  we  cannot 
even  conceive  of  their  num- 
ber. It  is  estimated  that 
the  brain  contains  9,000,000,- 
000  such  cells. 

We  may  think  of  one  of 
these  cells  as  a  tiny  battery 
which  can  start  nervous  im- 
pulses over  the  nerve  fibers 
leading  from  it,  or  as  a  bit  of 
apparatus  which  receives  im- 
pulses coming  over  other 
nerves.  Each  nerve  cell  is 
connected  by  a  long  nerve 
fiber  with  some  part  of  the 
body.  There  is  no  part  of 
the  body,  no  matter  how 
small,  that  is  not  connected 
with  the  nerve  cells  of  the  brain  and  spinal  cord. 

The  nerve  cells  in  the  brain  are,  most  of  them,  near 
the  surface.  The  rest  of  the  brain  consists  of  a  com- 
plex tangle  of  fibers  running  in  all  directions,  somewhat 
like  the  series  of  wires  that  run  into  a  central  telephone 
station ;  only  instead  of  a  few  hundred  such  wires  the 
brain  has  hundreds  of  thousands. 


FIG.  69.  —  A  NERVE  CELL. 

Showing  branches  and  a  single 

nerve  fiber  arising  from  it. 


THE  NERVOUS  SYSTEM  197 

QUESTIONS 

1.  What  is  the  relation  of  the  nervous  system  to  the  rest  of 
the  body? 

2.  What  is  the  brain? 

3.  What  are  the  parts  of  the  brain  ? 

4.  Where  is  the  medulla?    What  is  its  work? 

5.  If  the  cord  is  cut  across  below  the  medulla,  why  would 
breathing  stop  at  once? 

6.  What  is  the  cerebellum  ?    What  actions  does  it  control? 

7.  How  is  the  cerebrum  arranged?     What  powers  does  it 
control  ? 

8.  What  is  the  spinal  cord?    Where  is  it  situated? 

9.  What  does  a  cross  section  of  the  spinal  cord  show  of  its 
structure  ?    . 

10.  What  is  the  purpose  of  the  nerves? 

11.  If  the  posterior  root  of  a  nerve  (see  Fig.  67)  were  cut,  could 
the  person  receive  sensations  through  that  nerve  ?    Why  ? 

12.  How  do  the  brain  and  spinal  cord  resemble  an  electric 
battery? 

13.  Why  are  there  more  nerve  cells  in  the  brain  than  elsewhere? 


CHAPTER  XI 
THE  NERVOUS  SYSTEM   IN  ACTION 

DUTIES  OF  THE  NERVES 

IF  we  touch  the  hand  with  a  hot  match,  instantly  we 
have  a  feeling  of  pain  and  the  hand  is  drawn  away. 
The  hand  is  connected  with  the  brain  by  the  nerve 
shown  in  Figure  70.  If  this  nerve  of  the  arm  should 
be  cut  at  the  point  indicated  in  the  figure,  and  then  the 
match  should  be  touched  to  the  hand,  no  pain  would 
be  felt.  What  is  more,  if  we  should  wish  to  move  the 
hand,  we  should  be  quite  unable  to  do  so.  Cutting  the 
nerve,  therefore,  destroys  all  sensation  and  all  power 
of  motion  in  the  hand.  The  cutting  does  not  injure 
the  muscles.  They  would  still  be  able  to  contract,  if 
they  were  stimulated  by  an  electric  shock.  Moreover, 
cutting  does  not  destroy  sensation;  for  if  the  end  of 
the  nerve  which  is  still  attached  to  the  brain  (called 
the  central  end  in  Fig.  70)  were  pinched,  we  should 
feel  pain.  And  what  seems  most  strange  of  all,  we 
should  think  that  we  felt  the  pain  in  the  hand  and 
fingers,  although  the  nerve  had  really  been  touched  at 
a  point  above  the  elbow.  These  facts  teach  us  several 
things  in  regard  to  the  action  of  the  nerves. 

1.  The  nerves  form  a  line  of  communication  be- 
tween the  brain  and  spinal  cord  and  the  muscles. 
Muscles  are  caused  to  act  by  means  of  nerves. 

198 


THE  NERVOUS  SYSTEM  IN  ACTION 


199 


2.  Muscles  commonly  act  only  when  they  receive  a 
nervous  impulse  from  the  brain  or  spinal  cord. 

3.  Nerves  form  a  means  of  communication  between 
the  different  parts  of  the  body  and  the  brain,  by  which 
messages  (sensations  of  pain,  for  example)  are  sent  to 
the  brain. 

4.  Sensations  are  really  felt 
in  the  brain,  although  we  seem 
to  feel  them  in  other  parts  of 
the  body. 

The  burning  match  touched 
to  the  skin  of  the  hand  causes  a 
message  to  travel  up  the  nerve, 
but  no  feeling  of  pain  results 
unless  the  message  reaches  the 
brain.  When,  therefore,  the 
nerve  is  cut  or  compressed  so 
that  the  message  cannot  get  to 
the  brain,  no  sensa- 
tion of  pain  is  felt. 
If  the  message  does 
reach  the  brain, 
however,  it  produces 
pain,  and  we  locate 
this  pain  in  the  hand 
where  the  match  touched  it.  The  brain  always  locates 
the  pain  at  the  end  of  the  nerve  which  brings  the 
message,  and  for  this  reason  it  sometimes  makes  a 
mistake. 

For   example,  the  nerve  from  the  hand  has  all  our 


FIG.  70. 

Showing  the  connection  of  the  hand  with 
the  brain  by  a  nerve.  It  is  supposed 
to  be  cut  above  the  elbow. 


200  PHYSIOLOGY  AND  HYGIENE 

lives  brought  messages  to  the  brain  from  the  hand. 
Now  if  this  nerve  is  cut  above  the  elbow,  as  in  Figure  70, 
it  can  no  longer  bring  messages  from  the  hand.  But 
if  the  central  end,  also  shown  in  the  figure,  is  pinched, 
the  nerve  carries  the  impulse  to  the  brain.  Since  the 
brain  has  always  received  over  this  nerve  impulses 
coming  from  the  hand,  it  is  now  not  able  to  recognize 
that  this  impulse  does  not  come  from  the  same  place. 
So  the  sensation  seems  to  come  from  the  hand,  when  in 
reality  it  started  from  above  the  elbow. 

These  facts  make  it  clear  that  the  nerves  are  merely 
conducting  wires  carrying  impulses  that  start  at  their 
ends.  Some  impulses  start  at  the  outer  ends  and 
go  to  the  brain,  producing  sensation  there.  Other 
impulses  start  in  the  brain  and  pass  down  the  spinal 
cord  and  out  to  the  muscle  fibers,  where  they  cause 
motion  of  the  muscles.  Messages  travel  thus  through 
the  nerves  in  both  directions,  and  by  means  of  them 
the  brain  is  placed  in  communication  with  every  part 
of  the  body. 

The  nerve  fibers  by  means  of  which  sensation  is 
communicated  to  the  brain  are  called  sensory  nerve 
fibers.  Those  which  convey  the  impulses  from  the  brain 
to  the  muscles  are  called  motor  nerve  fibers. 

DUTIES   OF   THE    SPINAL   CORD   AND   MEDULLA 

The  spinal  cord  has  more  complicated  duties  to  per- 
form than  have  the  nerves.  Carrying  messages  to  and 
from  the  brain  is  simply  one  of  these  manifold  duties. 
As  can  be  seen  from  Figure  66,  large  numbers  of  nerves 


THE  NERVOUS  SYSTEM  IN  ACTION  201 

enter  the  spinal  cord,  and  in  the  cord  itself  they  pass 
up  to  the  brain.  These  nerves  are  all  so  arranged  that 
messages  passing  through  them  from  the  right  side  of 
the  brain  reach  the  left  side  of  the  body,  and  messages 
starting  from  the  right  side  of  the  body  reach  the  left 
side  of  the  brain. 

Independent  Action  of  the  Cord.  —  We  have  learned 
that  the  spinal  cord  contains  nerve  cells  as  well  as  nerve 
fibers.  If  these  nerve  cells  serve  the  same  purpose  as 
batteries,  we  should  naturally  expect  that  the  spinal 
cord  could  do  something  besides  simply  carry  messages. 
The  cord  does  indeed  have  another  kind  of  duty,  called 
reflex  action.  If,  for  example,  a  finger  is  pinched,  an 
impulse  is  started  which  passes  to  the  spinal  cord  on 
its  way  to  the  brain.  In  the  spinal  cord  it  excites 
certain  cells.  These  in  turn  excite  other  cells,  from 
which  instantly  motor  impulses  are  sent  out  from  the 
spinal  cord  to  the  muscles  controlling  the  arm  and 
hand,  causing  contraction  and  the  withdrawal  of  the 
finger.  This  is  called  reflex  action,  and  it  takes  place 
very  quickly  —  in  less  than  one  tenth  of  a  second. 
The  original  sensory  impulse,  of  course,  may  pass  on 
to  the  brain,  where  it  will  cause  pain,  but  the  instan- 
taneous withdrawal  of  the  finger  from  danger  was  a  re- 
flex action,  and  might  take  place  without  brain  action. 
Reflex  action  does  not  require  any  will  power  and  can 
take  place  just  as  well  when  a  person  or  an  animal  is 
asleep  as  when  he  is  awake.  In  the  case  of  some  ani- 
mals it  will  take  place  when  the  brain  has  been  entirely 
removed  from  the  body. 


202  PHYSIOLOGY  AND   HYGIENE 

A  reflex  action  never  starts  itself.  It  must  always 
be  started  by  some  outside  stimulus.  To  produce  such 
a  reflex  action  something  must  stimulate  the  body  in 
such  a  way  as  to  cause  a  message  to  go  to  the  spinal 
cord.  The  action  never  begins  in  the  spinal  cord  itself, 
but  always  at  the  outer  ends  of  the  nerves,  usually 
because  something  touches  the  skin  or  some  other  part 
of  the  body. 

Although  the  brain  is  not  necessary  to  reflex  action, 
still  it  is  possible  for  the  brain  partly  to  control  such 
action,  especially  if  the  action  is  a  repeated  one,  or  one 
of  which  we  are  aware  in  advance.  For  example,  if 
the  bottom  of  the  foot  is  tickled,  the  foot  is  pulled 
away.  This  is  a  reflex  action  and  will  take  place  when 
we  are  asleep  just  as  readily  as  when  we  are  awake. 
If,  however,  we  are  awake  and  know  what  is  to  be 
done,  we  can  often  use  sufficient  will  power  to  prevent 
the  foot  from  being  pulled  away  even  when  it  is 
tickled.  The  will  power  is  exerted  through  the  brain 
alone  and,  therefore,  in  this  case  the  brain  stops  the 
reflex  action.  But  under  some  circumstances,  even 
when  we  are  awake,  our  will  power  is  not  strong 
enough  to  prevent  the  reflex  action.  If  a  bit  of  food 
becomes  caught  in  the  windpipe,  for  instance,  it  will 
cause  us  to  cough,  and  no  matter  how  hard  we  try,  we 
shall  be  unable  to  keep  from  coughing  until  the  food  is 
dislodged.  The  coughing  is  a  reflex  action  and,  in  this 
case,  is  too  strong  to  be  controlled  by  will  power. 

Reflex  Action  in  the  Medulla.  —  A  study  of  the  me- 
dulla, indicated  in  Figure  65  as  at  the  top  of  the  spinal 


THE  NERVOUS  SYSTEM  IN  ACTION"  203 

cord,  shows  that  this  part  of  the  brain  controls  a 
number  of  the  most  important  vital  functions.  Here 
are  centered  the  powers  that  control  breathing,  the 
rapidity  of  the  heart  beat,  swallowing,  the  size  of  the 
blood  vessels  (thus  regulating  circulation),  and  some 
others  of  less  importance.  These  actions  are  all  reflex. 
It  will  be  recognized  that  these  actions  are  the  primary 
functions  of  life.  If  they  continue,  the  person  will 
live,  even  though  all  others  cease  for  a  time.  The 
activity  of  the  cerebellum  and  cerebrum  may  stop  for  a 
while  and  yet  the  person  may  continue  to  live  if  the 
medulla  is  not  injured;  but  if  the  medulla  is  injured, 
it  may  stop  the  heart  beat  and  breathing  at  once,  and 
thus  produce  instantaneous  death,  even  though  the  rest 
of  the  brain  is  uninjured.  The  medulla  may  thus  be 
said  to  be  the  center  of  the  vital  functions.  The  cen- 
ters controlling  these  vital  functions  may  act  quite 
independently  of  will  power  or  consciousness,  as  they 
do  when  we  are  asleep. 

THE  CEREBELLUM  AND  CEREBRUM 

The  Work  of  the  Cerebellum.  —  The  cerebellum  also 
controls  reflex  actions  more  complex  than  those  connected 
with  the  spinal  cord.  Such  actions  as  walking  are 
at  first  controlled  by  our  will  power  and  are  not  reflex 
at  all.  After  a  time,  however,  they  become  reflex  in  a 
measure,  and  take  care  .of  themselves.  When  we  first 
begin  learning  to  play  the  piano  we  must  think  care- 
fully of  the  action  of  each  finger,  but  after  playing  for 
a  number  of  years,  we  no  longer  need  to  attend  par- 


204  PHYSIOLOGY  AND  HYGIENE 

ticularly  to  the  fingers.  We  simply  place  our  hands 
on  the  piano  and  the  fingers  fall  naturally  upon  the 
proper  keys  and  make  the  proper  motions  for  pro- 
ducing music.  A  skilled  pianist  can  talk  to  a  friend 
and  at  the  same  time  continue  playing,  paying  no  atten- 
tion to  his  fingers  and  yet  never  striking  wrong  notes. 
Through  long  practice  certain  parts  of  his  brain,  prob- 
ably in  the  cerebellum,  have  learned  to  take  care  of  the 
motions  of  the  fingers,  so  that  the  mind  is  free  to 
attend  to  something  else.  Some  of  these  complex 
actions  are  controlled  by  the  cerebellum,  but  physiolo- 
gists as  yet  know  little  about  them  or  where  they  are 
located. 

The  Work  of  the  Cerebrum.  —  The  upper  and  larger 
part  of  the  brain,  the  cerebrum,  is  the  real  center  from 
which  all  the  impulses  of  our  conscious  activity  come. 
It  is  the  center  that  regulates  the  conscious  action  of 
the  whole  body. 

The  relation  of  the  cerebrum  to  the  other  parts  of 
the  body  may  be  best  understood  by  the  comparison 
already  used,  of  the  superintendent  and  the  factory. 
The  cerebrum  itself  is  like  the  general  superintendent 
who  directs  the  work  of  the  whole  factory.  The  vari- 
ous centers  in  the  cerebellum  and  the  spinal  cord  are 
like  the  foremen  of  different  rooms  or  of  different  parts 
of  the  work.  When  the  superintendent  wishes  some- 
thing to  be  done,  he  sends  a  message  to  the  foreman  of 
a  special  room,  and  the  foreman  gives  the  order  to  the 
individual  workmen.  In  this  way  the  superintendent 
is  not  obliged  to  pay  attention  to  the  detailed  work  of 


THE  NERVOUS   SYSTEM  IN  ACTION  205 

every  employee,  but  can  give  his  time  to  planning  the 
operations  of  the  factory  as  a  whole. 

So  the  mind^  when  it  wishes  some  special  action  to 
be  performedi^iicji  as  moving  the  hand,  sends  a  message 
to  some  of  the  centers  in  the  lower  parts  of  the  brain, 
and  these  forward  the  necessary  commands  by  way  of 
the  nerves  to  the  muscles  in  the  arm  and  hand,  so  that 
the  hand  is  moved.  After  the  various  centers  have 
learned  their  duty,  the  mind  itself  does  not  need  to 
attend  to  the  little  details.  Our  minds  are  then  free 
for  thought.  We  can  talk  as  we  play  on  the  piano 
because  the  mind  has  trained  some  of  its  servants 
in  the  cerebellum  to  look  after  the  contractions  which 
cause  the  fingers  to  touch  the  keys  correctly.  If  these 
servants  in  the  cerebellum  are  not  carefully  trained,  the 
plans  made  by  the  mind  will  not  be  properly  carried 
out.  Our  education,  from  the  time  of  our  earliest 
childhood,  is  largely  given  to  training  the  servants  of 
the  mind.  We  sometimes  call  the  training  of  these 
servants  acquiring  habits. 


THE  IMPORTANCE  OF  HABITS 

We  can  readily  see  how  necessary  it  is  that  we  should 
have  well-trained  servants  to  do  our  work,  and,  there- 
fore, that  we  should  form  good  habits.  After  we  have 
once  formed  a  habit  it  is  very  difficult  to  get  rid  of  it. 
The  training  of  children  at  home  and  at  school  is  for 
the  purpose  of  developing  right  habits  of  thinking  and 
acting,  in  order  that,  after  they  become  men  and 


206 


PHYSIOLOGY  AND  HYGIENE 


women,  they  may  be  properly  guided  by  these  good 
habits. 

By  doing  the  same  thing  again  and  again  the  body 
becomes  so  accustomed  to  a  certain  kind  of  action  that 


FIG.  71.  — THE  BRAIN  IN  POSITION. 
Showing  the  location  of  the  different  powers  in  the  brain. 

it  will  be  "second  nature"  to  perform  that  action. 
Every  time  that  we  do  something  in  a  certain  way  it 
becomes  easier  to  do  the  same  thing  in  that  way  again. 
If  the  habit  is  an  injurious  one,  like  the  alcohol  habit, 


THE  NERVOUS  SYSTEM  IN  ACTION  207 

we  come  more  and  more  under  its  influence  by  yielding 
to  it.  If,  on  the  other  hand,  the  habit  is  a  useful  one, 
we  fit  ourselves  better  for  life  every  time  we  perform 
the  action.  This  is  as  true  of  moral  actions  as  it  is  of 
muscular  movements.  If  we  exaggerate  the  facts  when 
we  tell  a  story,  we  are  forming  a  habit  that  will  grow 
until  we  become  liars,  unless  the  fault  is  overcome.  If 
we  dawdle  over  our  books  instead  of  giving  our  best 
thought  to  study,  we  are  forming  habits  of  inattention 
that  are  likely  to  hinder  successful  work  through  life. 
We  are  constantly  forming  habits  whether  we  wish  to 
do  so  or  not.  Inasmuch  as  these  habits  are  to  be  our 
servants  through  life,  it  is  wise  to  see  to  it  that  we  form 
those  that  will  be  useful  rather  than  those  that  may  do 
us  harm. 

We  know  very  little  in  regard  to  the  location  of  the 
different  powers  of  the  cerebrum.  Figure  71  indicates 
about  all  that  is  really  understood.  The  power  of  think- 
ing is  probably  connected  with  the  front  of  the  brain, 
certain  powers  of  motion  with  the  middle,  while  some 
of  the  senses  are  located  in  the  back  part  of  the  brain. 

THE  CARE  OF  THE  MIND 

Our  entire  lives  are  directed  by  the  mind.  We 
should,  then,  take  the  best  possible  care  of  these  minds 
of  ours.  A  few  facts  of  importance  are  worth  remem- 
bering. 

Sleep.  —  We  cannot  continue  one  form  of  activity 
very  long  without  some  kind  of  rest,  for  both  the  body 
and  the  mind  need  to  rest.  The  most  complete  kind 


208  PHYSIOLOGY   AND  HYGIENE 

of  rest  for  mind  and  body  is  sleep.  When  we  sleep, 
the  mind  is  largely  free  from  its  usual  forms  of  activ- 
ity, although  our  dreams  show  us  that  the  mind  is  not 
entirely  inactive.  The  deeper  the  sleep  the  less  distinct 
will  be  the  dreams.  The  amount  of  sleep  needed  by 
various  people  differs  greatly.  A  young  child  needs 
twelve  hours  out  of  the  twenty-four  for  sleep,  a  growing 
boy  or  girl  about  ten,  while  most  grown  people  require 
only  about  seven  or  eight.  Some  persons  seem  to  get 
on  very  comfortably  with  even  less.  It  is  best  to 
remember,  however,  that  we  are  much  more  likely  to 
have  too  little  sleep  than  too  much. 

Sometimes  a  boy  or  girl  takes  a  kind  of  pride  in 
sitting  up  late  and  studying  far  into  the  night.  This 
is  likely  to  be  done  just  before  examination  time, 
under  the  impression  that  better  preparation  can  thus 
be  made  for  the  tests.  This  is  a  great  mistake.  Sit- 
ting up  late  to  study,  the  night  before,  usually  renders 
one  less  fitted  to  pass  an  examination.  The  many  facts 
we  try  to  cram  into  our  heads  during  such  midnight 
study  are  not  all  found  there  the  next  morning.  We 
are  weary,  and  the  brain  does  not  work  as  it  should. 
To  get  a  good  night's  rest  is  a  much  better  method  of 
preparing  for  an  examination  than  to  study  until  the 
mind  gets  tired. 

Concentration.  —  The  person  who  accomplishes  the 
most  is  the  one  who  is  able  to  turn  his  whole  attention 
to  his  work.  When  we  are  thinking  of  several  things 
at  once,  we  can  give  none  of  them  careful  considera- 
tion. If,  when  we  are  supposed  to  be  studying,  we  let 


THE  NERVOUS   SYSTEM  IN  ACTION  209 

our  thoughts  wander  to  the  athletic  field,  then  to  the 
woods  and  the  trout  brook,  then  to  something  going  on 
in  the  schoolroom,  bringing  them  back  finally  with  an 
effort  to  the  lesson,  it  will  take  us  much  longer  to  master 
,.  the  lesson  than  it  will  if  we  give  our  attention  to  that 
and  nothing  else.  The  pupil  who  applies  his  mind 
wholly  to  the  lesson  he  is  preparing  will  do  his  work 
much  more  quickly  and  much  better  than  his  neighbor 
across  the  aisle  who  studies  one  minute  ancRtreams  the 
next.  The  ability  to  think  of  one  thing  at  a  time  is 
largely  a  habit,  and  one  of  the  most  useful  of  habits. 
It  is  one  that  can  and  should  be  acquired  by  every  boy 
and  girl.  If  we  allow  our  thoughts  to  wander  from 
one  thing  to  another,  we  shall  let  this  habit  master  us, 
and  in  later  life  we  may,  as  a  result,  find  it  very  diffi- 
cult to  think  continuously  and  vigorously. 

Recreation.  —  The  mind  needs  recreation  as  well  as 
work  and  rest.  It  ought  to  be  employed  at  times  in 
such  a  way  as  to  obtain  relief  from  its  required  tasks. 
We  ought  just  as  much  to  give  our  minds  recreation  as 
to  give  them  sleep.  Without  it  we  become  dull,  and 
our  bodily  health  is  likely  to  suffer.  Recreation  is 
even  more  necessary  for  the  boy  or  girl  who  wishes  to 
be  a  scholar  than  it  is  for  the  person  who  works  prin- 
cipally with  his  muscles. 

Each  of  us  should  choose  his  own  recreation.  It 
should  be  something  that  gives  pleasure  and  enjoyment, 
and  it  must  be  something  that  we  do  from  choice,  not 
because  we  must.  It  is  also  necessary  that  the  kind 
of  recreation  a  person  takes  should  occasionally  be 


210  PHYSIOLOGY  AND  HYGIENE 

changed.  Much  of  a  person's  success  as  well  as  happi- 
ness in  life  depends  upon  his  having  enjoyment.  We 
can  work  harder  and  do  better,  if  we  may  look  forward 
to  pleasant  recreation  as  the  reward  for  faithful  labor, 

Dependence  of  the  Mind  upon  the  Body.  —  Our  minds 
and  our  bodies  are  related  so  closely  that  their  welfare 
cannot  be  separated.  If  we  allow  our  bodies  to  become 
weak  from  lack  of  exercise  or  want  of  the  proper  kinds 
of  food,  our  minds  will  not  be  vigorous.  The  most 
active  mind,  and  the  one  that  thinks  best,  will  be  found 
in  a  healthy  body.  The  boy  or  girl  who  enjoys  books 
and  study  is  the  one  who  must  be  especially  careful  to 
give  proper  attention  to  health.  The  student  must 
have  recreation,  exercise,  good,  wholesome  food,  fresh 
air  and  sunshine,  if  he  wishes  to  preserve  at  its  best 
that  valuable  treasure,  his  mind.  The  boy  or  girl  who 
neglects  mind  for  body  cannot  compete  in  after  life  with 
the  person  who  studies  hard.  On  the  other  hand,  the 
boy  or  girl  who  neglects  bodily  health  for  the  sake  of 
knowledge  is  sure  to  fall  behind  the  one  who  develops 
a  healthy  mind  in  a  healthy  body. 

The  Mind  and  Narcotics. — One  matter  of  importance 
in  connection  with  the  proper  care  of  the  mind  is  keep- 
ing it  free  from  the  control  of  all  narcotics.  The  use  of 
alcohol  has  its  first  and  most  important  effect  upon  the 
action  of  the  brain.  The  first  result  of  taking  alcohol 
seems  to  be  to  excite  the  brain,  and  thus  alcohol  has  been 
wrongly  called  a  stimulant.  This  excitation  is  really 
one  of  the  results  of  its  narcotic  action.  Its  action  upon 
the  brain  is  really  the  opposite  of  a  stimulant,  for  almost 


THE   NERVOUS   SYSTEM  IN  ACTION  211 

at  once  it  begins  to  dull  the  mental  powers.  This  dulling 
action  becomes  very  noticeable  when  large  amounts  of 
alcohol  are  used. 

Careful  testing  has  shown  that  one  who  has  taken 
even  small  quantities  of  alcohol  cannot  add  a  column 
of  figures  so  quickly  as  usual,  or  that  if  he  can  add 
the  column  as  quickly  he  may  fail  to  do  it  accurately. 
He  may  be  able  to  talk  more  rapidly,  but  he  will  com- 
monly not  think  so  clearly.  He  acts  more  slowly  than 
usual.  If  he  is  hunting,  he  loses  his  straight  aim ;  if 
setting  type,  he  works  less  rapidly  and  makes  more 
mistakes.  He  is  perhaps  not  conscious  of  all  this,  and 
feeling  somewhat  excited  and  exhilarated,  he  may 
actually  think  that  he  is  doing  more  work  than  usual, 
while  he  is  really  doing  less.  He  may  believe  himself 
to  be  bright  and  witty,  when  he  is  uttering  only  foolish 
jests.  The  man  with  whom  he  has  business  dealings, 
and  who  keeps  sober,  gets  the  better  of  him  in  a  bargain. 
The  more  alcohol  he  uses,  the  greater  its  dulling  action 
on  the  brain.  Finally  he  may  notice  it  himself,  but 
even  though  he  does  not  appreciate  it,  others  find  that 
he  is  not  able  to  talk  intelligently  ;  he  becomes  confused 
and  stupid,  and  finally  is  unable  even  to  walk  straight. 
When  he  is  completely  under  the  influence  of  alcohol, 
nearly  all  the  actions  of  his  body  cease,  except  breathing 
and  the  beating  of  the  heart. 

There  are  various  degrees  in  this  dulling  effect  of 
alcohol.  It  is  slight  when  small  amounts  are  used,  and 
complete  when  large  quantities  are  taken.  How  large 
an  amount  a  person  can  take  without  having  his  judg- 


212  PHYSIOLOGY  AND   HYGIENE 

ment  seriously  affected  it  is  impossible  to  say.  But 
even  the  very  small  amounts  appear  to  have  some 
dulling  action  upon  the  mind.  Some  of  the  keenest 
thinkers  have  found  that  their  power  of  concentrated 
thought  is  dulled  by  taking  even  very  small  amounts  of 
alcohol.  The  primary  effect  of  alcohol  is  to  disorganize 
the  nervous  system.  Its  effect  may  be  slight  if  only 
small  amounts  are  used,  but  the  effect  is  nevertheless 
there,  the  same  in  kind,  though  less  in  degree  even  when 
small  amounts  are  taken. 

QUESTIONS 

1.  How  do  we  know  that  sensations  are  felt  only  in  the  brain? 

2.  If  the  spinal  cord  were  cut  across  at  the  shoulders,  what 
effect  would  it  have  on  the  lower  parts  of  the  body  ? 

3.  What  have  the  nerves  to  do  with  sensation  ? 

4.  What  is  reflex  action? 

5.  Where  is  reflex  action  controlled? 

6.  If  a  person's  foot  is  tickled,  what  action  and  reflex  actiou 
occur?    Do  you  suppose  the  foot  would  be  pulled  away  if  tha 
person  were  asleep  ? 

7.  What  reflex  actions  are  controlled  by  the  medulla  ? 

8.  What  kind  of  reflex  actions  are  controlled  by  the  cerebellum? 

9.  Why  should  you  think  coughing  to  be  a  reflex  action? 

10.  What  are  the  duties  of  the  cerebrum  ? 

11.  Why  is  it  important  that  good  habits  be  formed  ? 

12.  In  what  ways  can  the  mind  be  cared  for  ? 

13.  Why  is  sleep  necessary  ? 

14.  If  a  person  goes  to  sleep  while  sitting  up,  he  is  likely  to  fall 
over.    Why  is  this?    Would  he  be  as  liable  to  fall  over  as  he 
would  be  if  he  fainted? 

15.  Why  should  we  learn  the  habit  of  concentration?    Ho\v 
may  it  be  learned? 

16.  What  is  recreation  ?    Why  is  it  necessary? 

17.  What  is  the  effect  of  alcohol  upon  the  mind? 


CHAPTER  XII 
THE  SENSES 

THE  brain  is  shut  up  tight  in  its  bony  box,  the  skull. 
It  has  no  direct  contact  with  the  external  world,  and 
yet  it  succeeds  in  finding  out  very  well  what  is  going 
on  outside  of  our  bodies,  just  as  a  telegraph  operator, 
shut  up  in  his  little  office,  can  learn  what  is  going  on 
in  the  world.  As  we  have  learned,  the  brain  is  con- 
nected with  the  outer  parts  of  the  body  by  the  sensory 
nerves,  which  bring  messages,  or  impulses,  from  the 
exterior.  They  extend  from  every  part  of  the  body  to 
the  spinal  cord  and  the  brain,  and  bring  messages  from 
every  part.  The  messages,  when  they  reach  the  brain, 
produce  what  are  called  sensations,  and  it  is  through 
the  sensations  that  we  get  our  knowledge  of  the  outer 
world. 

There  are  several  outside  forces  that  may  excite  the 
sensory  nerves  to  send  impulses  to  the  brain.  One  of 
the  most  common  of  these  is  a  touch  upon  the  skin, 
which  sends  an  impulse  that  gives  rise  in  the  brain  to 
a  sensation  which  we  call  touch.  Similar  sensations 
can  come  from  every  part  of  the  skin.  There  are  also 
several  forces  capable  of  starting  impulses  through  spe- 
cial nerves.  Light,  for  example,  starts  impulses  from, 
the  eye  through  its  nerve.,  sound  from  the  earo  Through 

213 


214 


PHYSIOLOGY  AND   HYGIENE 


these  special  nerves  we  get  our  sense  of  sight  and  of 
hearing.  Some  substances  excite  impulses  from  the 
tongue,  giving  a  sense  of  taste,  and  others  from  the 
nose,  giving  the  sense  of  smell.  These  act  by  means 
of  special  organs,  situated  at  the  ends  of  particular 
nerves,  which  we  call  sense  organs.  These  represent 
four  of  the  so-called  special  senses. 

THE  SENSE  OF  SIGHT 


Lachrymal  Gland 


The  Eyeball.  —  The  eye  itself  is  shaped  like  a  ball,  as 
shown  in  Figure  73,  although  as  we  look  at  it  in  a  person's 

face  it  appears  quite 
unlike  a  sphere.  This 
is  because  we  see  only 
a  small  portion  of  the 
front  of  the  eye,  the 
rest  being  hidden  be- 
hind the  eyelids.  The 
only  part  of  the  eye- 
ball that  we  can  see  is 
just  what  appears  be- 
tween the  eyelids,  and 
the  eye  will  look 
large  or  small  accord- 
ing to  whether  the  eyelids  are  wide  open  or  partly 
closed.  Different  people  appear  to  have  eyes  of  vari- 
ous sizes,  but  the  dimensions  are  really  always  about 
the  same ;  that  is,  the  diameter  is  close  to  one  inch. 

The %  eyeballs  are  set  in  deep  sockets  in  the  front 
of  the  skull,  as  may  be  seen  from  Figure  73,  only  the 


FIG.  72.  — THE  EYE,  VIEWED  FROM  IN 

FRONT. 
Showing  the  tear  gland  and  tear  duct. 


THE   SENSES  215 

front  surfaces  being  exposed.     The  sockets  protect  the 
balls  from  injuries  which  might  come  from  blows. 

The  Eyelids.  —  Two  folds  of  skin  hang  over  the  eye, 
one  above  and  the  other  below,  as  may  be  seen  in  Figure 
73.  These  are  eyelids,  which  open  and  close  over  the 
eye.  When  closed,  they  serve  to  protect  the  eye  and 
also  to  keep  its  surface  clean  and  moist.  Even  when  we 
are  awake  the  eyelids  close  every  few  seconds.  We  are 
quite  unconscious  of  this  movement  of  the  eyelids,  but 
we  can  easily  observe  it  by  watching  the  eyes  of  some 
one  near  us.  The  front  of  the  eye  is  extremely  delicate, 
and  if  the  lids  did  not  constantly  cleanse  its  surface, 
and  if  the  tear  secretions  did  not  wash  the  dust  away, 
the  eye  would  become  inflamed,  and  the  sight  be  affected. 
The  eyelids,  by  means  of  their  long  lashes  and  their 
exceedingly  quick  motion,  serve  also  to  guard  the  eye 
against  accident.  The  hairs  on  the  edges  of  the  lids, 
called  the  eyelashes,  assist  in  keeping  out  the  dust. 

The  Tear  Gland.  —  The  lids  are  aided  in  keeping  the 
eyes  clear  by  the  tears.  A  small  lachrymal  gland,  or 
tear  gland,  is  lodged  just  above  each  eye,  on  the  side 
away  from  the  nose.  This  gland  produces  a  watery 
liquid,  which  flows  down  over  the  eye  and  keeps  its 
surface  moist.  The  liquid  flows  over  the  eyeball  to 
the  inner  edge  of  the  eye  near  the  nose,  where  there  is 
a  tube,  the  tear  duct,  leading  to  the  cavity  inside  the 
nose,  as  shown  in  Figure  72.  The  tears,  after  washing 
the  surface  of  the  eye,  pass  through  the  duct  into  the 
nose  and  the  throat,  and  are  then  swallowed.  Usu- 
ally the  gland  produces  just  liquid  enough  to  wash  the 


216  PHYSIOLOGY  AND  HYGIENE 

eyeballs  and  to  pass  easily  down  the  lachrymal  duct 
But  when  a  person  cries,  the  tears  are  produced  so 


FIG.  73.  —  THE  EYE,  VIEWED  FROM  THE  SIDE. 
Showing  its  shape,  the  socket,  and  the  attachment  of  muscles. 

• 

rapidly  that  they  cannot  all  pass  through  the  duct  into 
the  nose.  They  then  overflow  and  run  down  the  cheeks. 

The  Eye  Muscles.  —  Six  small  muscles  are  attached  to 
each  eyeball  to  move  it.  One  is  on  the  top,  one  on  the 
bottom,  one  on  each  side,  and  two  others  have  an  oblique 
position.  Figure  73  shows  the  form  and  position  of 
these  muscles.  By  the  contraction  of  the  muscles  the 
eyeball  can  be  turned  in  any  desired  direction. 

Structure  of  the  Eyeball.  —  If  we  examine  a  photog- 
rapher's camera,  we  find  that  it  has  three  chief  parts. 
There  is  (1)  a  dark  chamber,  the  box  of  the  camera, 
closed  so  as  to  admit  light  only  from  the  front.  In  the 
opening  in  front  which  admits  the  light  there  is  (2)  a 
lens,  which  makes  an  image  of  the  object  to  be  photo- 


THE   SENSES 


217 


graphed ;  at  the  back  of  the  camera  is  (3)  the  sensitive 
plate,  upon  which  the  picture  is  taken. 

The  human  eye  is  made  upon  much  the  same  plan 
as  the  camera,  although  differing  in  details.     Like  the 
camera,  it   has  a   dark 
chamber  and  a  lens,  and 
also  a  sensitive  surface 

at  the  back.     If  we  ex-  .--- 

s=atf  image' 

amme  £  igure  74,  we  can 

see  how  closely  the  eye 
and  the  camera  may  be 
compared.  The  eyeball 
is  a  dark  chamber,  which, 
like  the  camera,  admits 
light  only  from  the 
front.  At  the  point 
where  the  light  is  ad- 
mitted there  is  a  lens, 
shown  in  Figure  74,  and 
at  the  back  of  the  eyeball  is  a  sensitive  surface  called 
the  retina,  shown  in  Figure  75.  Between  the  front  of 
the  eye  and  the  retina  the  eyeball  is  filled  with  trans- 
parent liquids,  through  which  the  light  can  easily  pass. 
Light  enters  the  eye  from  the  front,  passing  through 
the  small  opening  known  as  the  pupil  (Fig.  75). 
Just  inside  of  this  pupil  is  a  transparent  lens.  The 
lens  is  so  shaped  that  the  rays  of  light  are  changed  in 
their  direction  and  come  together  at  the  bacji  part  of 
the  eye.  When  they  come  together  they  produce  a 
little  picture  or  image  of  the  objects  from  which  the 


FIG.  74.  —  A  COMPARISON  OF  THE 
STRUCTURE  OF  THE  CAMERA  AND 
THE  EYE. 


218  PHYSIOLOGY  AND  HYGIENE 

light  comes.     This  image  is  similar  to  what  we  see  on 
the  ground-glass  screen  at  the  back  of  a  photographer's 


Co/ne 


FIG.  75.  —  A  DIAGRAM  REPRESENTING  A  SECTION  THROUGH 

THE  HUMAN  EYE. 
t 

camera,  which  shows  a  picture  of  the  objects  toward 
which  the  camera  is  pointed.  In  the  same  way  a  little 
picture  is  formed  upon  the  back  part  of  the  eye.  The 
part  of  the  eye  upon  which  the  image  is  formed  is  the 
retina,  and  is  the  sensitive  part. 

The  retina  is  full  of  nerves,  and  in  some  wonderful 
way,  not  fully  understood,  these  nerves  send  impulses 
to  the  brain,  by  which  the  brain  receives  and  recognizes 
the  picture.  If  the  nerves  that  connect  the  eye  with  tfye 
brain  were  cut,  the  message  could  never  reach  the  brain, 
even  though  the  image  should  be  formed  on  the  retina. 
If  the  eye  were  injured  so  that  the  image  could  not  be 
formed  on  the  retina,  we  could  not  see,  even  though  the 
nerve  were  in  good  condition. 


THE  SENSES  219 

V 

The  lens  that  forms  the  picture  on  the  retina  is  not 
able  to  form  a  picture  of  both  a  near  and  a  distant 
object  at  the  same  time  ;  hence  we  cannot  see  clearly 
near  objects  and  distant  objects  at  the  same  moment.  If 
we  are  observing  a  hill  some  distance  off,  and  wish  to 
look  at  a  pencil  in  our  hands,  the  shape  of  the  lens 
changes  a  little  so  that  the  pencil  becomes  sharply 
pictured  on  the  retina,  but,  at  the  same  time,  the  hill 
necessarily  becomes  blurred  to  our  sight. 

Nearsightedness.  —  If  the  eyeball  is  of  exactly  the 
right  shape,  ordinary  objects  will  be  sharply  pictured 
upon  the  retina.  If,  however,  the  ball  is  a  little  too 
long,  distant  objects  will  not  be  clear,  not  sharply 
focused  as  we  say,  but  they  will  look  blurred.  A  per- 
son with  such  eyes  cannot  see  distant  objects  clearly, 
though  he  can  readily  see  objects  quite  close  to  the 
eyes.  We  say  he  is  nearsighted,  and,  in  order  to  see 
clearly,  he  is  obliged  to  wear  glasses  especially  prepared 
to  overcome  his  difficulty. 

Nearsightedness  is  very  common.  It  is  often  due  to 
improper  habits  of  study.  We  are  likely  to  lean  over 
a  desk  or  a  table  when  we  read,  thus  bringing  the  book 
very  close  to  the  eyes.  This  habit,  if  continued,  is 
certain  to  cause  such  changes  that  the  eyes,  which  at 
first  could  see  clearly,  become  little  by  little  so  affected 
that  only  near  objects  can  be  clearly  seen.  Such  near- 
sightedness  is  quite  common  among  people  who  spend 
their  early  years  in  study.  The  difficulty  is  less  com- 
mon among  those  who  live  out  of  doors  and  who  do 
little  or  no  reading.  If  we  will  take  pains  to  sit  erect 


220  PHYSIOLOGY  AND  HYGIENE 

when  reading  or  studying,  and  to  hold  our  books  no 
nearer  than  a  foot  or  eighteen  inches  from  the  eyes. 
If  this  is  not  a  comfortable  distance,  the  eyes  need  the 
attention  of  an  oculist.  If  we  hold  a  book  within 
six  inches  of  the  eyes,  we  shall  be  quite  sure  to 
develop  nearsightedness. 

Color  Blindness.  —  Some  people  have  the  sense  of 
color  poorly  developed,  and  we  call  them  color  blind. 
This  does  not  mean  that  they  cannot  see  any  color  at 
all,  but  that  they  confuse  the  various  colors.  The 
most  common  form  of  color  blindness  is  the  inability 
to  distinguish  clearly  reds  from  greens.  Since  red  and 
green  are  the  colors  used  as  signals  on  railroads  and 
steamboats,  a  pilot  or  a  railroad  engineer  who  cannot 
distinguish  them  readily  may  commit  such  blunders 
that  accidents  will  result.  Persons  who  are  to  hold 
responsible  positions  on  railroads  or  steamboats  are 
accordingly  required  to  have  their  eyes  specially  tested 
for  color,  and  no  one  who  is  color  blind  should  ever 
think  of  taking  such  a  position.  The  difficulty  is  more 
common  among  men  than  among  women,  and  no  remedy 
for  it  is  known. 

Care  of  the  Eyes.  —  1.  The  eyes  were  made  to  be 
used,  and  it  does  them  no  harm  to  exercise  them  con- 
stantly. If,  however,  they  are  used  on  work  that 
requires  close  attention,  such  as  reading  or  sewing, 
they  become  tired  and  should  frequently  be  allowed  a 
moment  for  rest,  such  as  is  gained  by  closing  the  eye- 
lids or  by  looking  at  distant  objects. 

2.    We  should  not  abuse  the  eyes  by  reading  in  a 


THE  SENSES  221 

dim  or  flickering  light.  Nor  should  a  bright  light,  like 
the  sun's  rays,  be  allowed  to  fall  upon  the  page  we  are 
reading.  We  should  never  look  directly  at  a  bright 
light.  Daylight  is  better  than  artificial  light. 

3.  The  only  proper  position  for  holding  the  head 
when  we  read  is  erect.     Reading,  when  lying  on  the 
back  or  in  a  hammock,  is  very  injurious  to  the  eyes. 
We   must   not   forget,  moreover,  that   using  the  eyes 
means  also  working   the   brain.     When  the   brain   is 
tired,  one  is  often  inclined  to  lie  down  and  read  a  book 
—  setting   the   tired   brain   to  work  again,  and  under 
conditions  bad  for  the  eyes  themselves. 

4.  If  a  child  has  difficulty  in  seeing  or  his  eyes  are 
inflamed,  he  should  be.  examined  by  an  oculist.      Head- 
aches are  frequently  due  to  trouble  with  the  eyes,  and  if  a 
child  has  a  tendency  to  headache,  his  eyes  should  be 
examined.      It   frequently   happens   that    the   trouble 
with  the  head  may  be  cured  by  the  use  of  glasses  pre- 
scribed by  a  competent  oculist. 

5.  Particles   of    dust   that    get    into  the  eyes   are 
usually   carried   off   with    the    tears    by   way   of   the 
tear  duct,  and  a  few  winks  remove  them.     If  this  is 
not  sufficient,  the  trouble  may  frequently  be  remedied 
by  lifting  the  upper  eyelid  with  the  fingers  and  drawing 
it  down  over  the  lower  eyelid.     If  this  does  not  remove 
the  particle  of  dust,  it  may  be  taken  out  by  some  com- 
petent person  who  can  pass  gently  over  the  eyeball  the 
end  of  a  soft  handkerchief  rolled  up  to  a  point.     If  this 
attempt  fails,  a  physician  should  be  called.     The  eyes, 
in  such  cases,  should  never  be  rubbed.     The  eyes  are 


222 


PHYSIOLOGY   AND   HYGIENE 


organs  too  delicate  and  too  important  to  be  treated  by 
incompetent  persons.  If  one  has  trouble  of  any  kind 
with  his  eyes,  he  should  consult  a  physician  or  an 
oculist. 

THE  SENSE  OF  HEARING 

The  Ears.  — The  two  projections  on  the  sides  of  the 
head,  which  we  commonly  call  the  ears,  have  very  lit- 


Euatochian 
Tube,,  tothe 
throat 

FIG.  76.  — THE  EAR. 
A  section  through  the  "  stony  bone,"  showing  the  parts  of  the  ear. 

tie  to  do  with  hearing.  They  are  only  bits  of  carti- 
lage covered  with  skin,  which  serve,  perhaps,  to  col- 
lect waves  of  air,  and  probably  make  sounds  a  little 
louder.  The  real  hearing  organ  is  the  inner,  or  true 
ear,  which  is  wholly  inside  the  head  and  embedded  in 
the  bones.  The  ear  itself  is  in  the  middle  of  the 
hardest  bone  in  the  body,  called  the  stony  bone.  The 


THE   SENSES  223 

ear  is  thus  more   thoroughly  protected  from  external 
injury  than  any  other  organ. 

The  ear  is  a  very  complicated  organ.  Its  general 
structure  may  be  seen  from  Figure  76,  which  shows  a  sec- 
tion through  the  side  of  the  head,  giving  the  chief  parts 
of  the  ear.  The  passage  from  the  outside  to  the  true 
ear,  as  the  figure  shows,  is  slightly  bent.  In  it  there  is 
secreted  a  little  wax,  which  helps  keep  it  moist  and  flexi- 
ble. The  passage  is  closed  at  the  inner  edge  by  a  mem- 
brane which  is  stretched  across.  This  is  the  tympanic 
membrane.  Is  is  tough  and  elastic.  Earache  in  chil- 
dren is  usually  caused  by  sores  in  the  ear ;  these  occa- 
sionally make  little  holes  through  the  membrane,  which 
interfere  somewhat  with  hearing.  Sometimes  very  loud 
noises,  like  explosions,  break  the  membrane  and  make 
the  person  deaf. 

Figure  76  shows  that  beyond  the  membrane  there 
is  a  cavity.  It  is  known  as  the  ear  drum,  or  tympanic 
cavity,  and  is  also  sometimes  called  the  middle  ear. 
The  ear  drum  is  filled  with  air,  which  enters  it  through 
a  tube  in  the  lower  side.  This  tube  leads  to  the 
throat,  as  indicated  in  Figure  76,  and  is  opened  every 
time  we  swallow.  In  this  way  the  drum  is  filled  with 
air,  and  the  pressure  of  the  air  in  the  drum  is  kept  the 
same  as  the  pressure  of  the  air  outside.  If  this  tube 
becomes  closed,  as  sometimes  happens  with  inflamma- 
tion of  throat  or  nose,  the  air  within  the  ear  is  partly 
absorbed,  so  that  the  pressure  inside  becomes  less  and 
the  membrane  is  pushed  in  by  the  pressure  of  the  out- 
side air.  This  affects  the  hearing  injuriously.  This 


224  PHYSIOLOGY   AND   HYGIENE 

is  the  reason  why  throat  troubles  are  very  apt  to  extend 
to  the  ears  and  interfere  with  hearing.  Indeed,  the 
most  common  cause  of  deafness  is  to  be  found  in  diffi- 
culties of  the  throat.  Catarrh  in  the  throat  is  one  of 
the  first  things  that  a  physician  attends  to  in  most  cases 
of  difficulty  in  hearing. 

In  Figure  76  it  will  be  seen  that  three  small  bones 
(malleus,  incus,  and  stapes)  are  stretched  across  the 
cavity  of  the  middle  ear.  The  outer  of  these  ear  bones 
is  attached  to  the  membrane  and  the  inner  one  con- 
nects with  the  inner  ear,  which  contains  the  real  hearing 
organ.  In  this  inner  ear  are  many  nerves.  Sound  is 
produced  by  waves  of  air  which  enter  the  ear  and  shake 
the  tympanic  membrane.  This  shakes  the  bones  at- 
tached to  it,  and  by  their  motion  the  effect  of  the  air 
wave  is  transferred  to  the  inner  ear,  where  it  reaches 
the  nerves.  This  shaking  or  vibration  upon  the  nerves 
starts  nervous  impulses  which  travel  rapidly  to  the 
brain.  When  the  messages  reach  the  brain  they  pro- 
duce a  sensation  which  we  call  hearing. 

Hearing.  —  Our  ears  tell  us  very  little  in  regard  to 
sounds  except  their  loudness  or  softness,  aiid  their 
pitch  (high  or  low).  Our  power  of  determining  dis- 
tance is  limited.  If  we  know  what  causes  a  certain 
sound,  we  can  determine  something  of  its  distance  by 
the  loudness.  We  judge  the  distance  simply  by  the 
loudness  of  the  sound  as  compared  with  what  we  should 
hear  if  the  sound  were  nearer  or  farther  away.  If,  for 
example,  we  hear  the  whistle  of  a  locomotive,  and  it 
sounds  faint,  we  are  sure  that  the  engine  must  be  a  long 


THE  SENSES  225 

distance  away,  because  we  know  that  the  sound  itself  is 
really  very  loud.  If,  on  the  other  hand,  we  hear  the 
buzz  of  a  mosquito,  and  it  sounds  loud,  we  know  that 
the  insect  is  close  to  the  ear.  We  can  determine  the 
distance  of  sound  in  no  other  way  than  by  the  compara- 
tive loudness. 

Our  power  of  determining  the  direction  from  which 
sound  comes  is  not  much  greater.  Noises  coming  to 
the  ear  from  the  side  of  the  head  may  sound  louder  in 
one  ear  than  they  do  in  the  other,  and  in  that  case  we 
judge  that  the  sound  is  on  the  side  of  the  head  where  it 
seems  loudest.  Sometimes  we  unconsciously  turn  the 
head  around  a  little,  until  we  find  that  the  sound  appears 
to  be  loudest  when  the  head  is  in  a  certain  position. 
We  then  conclude  that  the  noise  comes  from  the  direc- 
tion toward  which  the  ear  is  turned.  But  this  test  is 
by  no  means  accurate. 

Care  of  the  Ears.  —  The  ears  require  very  little  care. 
The  use  of  solid  objects,  like  pins  or  needles,  to  remove 
the  ear  wax  is  very  unsafe.  The  ears  may  be  kept  suffi- 
ciently clear  of  wax  by  means  of  the  little  finger,  which 
should  be  pushed  downward  as  it  is  placed  in  the  open- 
ing. Very  loud  sounds  close  to  the  head  are  likely  to 
do  harm.  Boxing  children's  ears  is  liable  to  injure  the 
membranes  within.  Pain  in  the  ear  may  sometimes  be 
relieved  by  placing  hot  cloths  upon  the  ear ;  but  if  it 
persists,  a  physician  should  be  called.  It  is  well  to  re- 
member that  deafness  is  most  commonly  produced  by 
throat  troubles,  and  if  one  has  any  difficulty  in  hearing, 
he  should  first  of  all  look  to  the  condition  of  his  throat. 


226  PHYSIOLOGY  AND   HYGIENE 

Slight  deafness  is  not  unusual  with  children  ;  it  renders 
a  pupil  apparently  inattentive  and  dull.  The  child  does 
not  realize  that  he  has  any  difficulty  in  hearing,  and 
very  likely  neither  his  teacher  nor  his  parents  suspect  it. 
Therefore  a  child  who  is  inattentive  should  have  his 
hearing  tested.  If  deafness  is  the  cause  of  the  difficulty, 
a  physician  should  be  consulted  at  once  to  remedy  the 
defect,  if  possible. 

THE  SENSE  OF  TASTE 

By  the  sense  of  taste  we  learn  something  of  the  nature 
of  liquids.  Solid  substances  do  riot  produce  taste.  It 
is  true  that  many  solid  bodies  have  a  certain  taste,  when 
taken  into  the  mouth,  but  not  until  they  are  more  or 
less  dissolved  in  the  saliva.  If  we  rub  the  tongue  dry, 
and  then  place  upon  it  a  lump  of  sugar,  we  notice  no 
taste  at  first,  but,  as  soon  as  the  liquids  of  the  mouth 
begin  to  dissolve  the  sugar,  we  perceive  the  sweet  taste. 

Location. — The  sense  of  taste  is  located  in  the  mouth, 
but  not,  as  is  commonly  supposed,  wholly  in  the  tongue. 
The  upper  side  of  the  tongue  has  a  sense  of  taste,  but 
the  under  side  has  not.  Besides  this,  the  roof  of  the 
mouth,  especially  at  the  back,  has  a  sense  of  taste.  When 
a  substance  is  rolled  around  by  the  tongue  at  the  back 
of  the  mouth,  we  find  there  the  strongest  sense  of  taste. 

The  Tongue.  —  The  tongue  of  a  healthy  person  is  of  a 
pinkish  red  color.  If  it  is  otherwise,  the  stomach  is 
probably  out  of  order.  One  of  the  simplest  methods 
employed  by  physicians  for  detecting  signs  of  certain 
diseases  is  an  examination  of  the  tongue.  When  this  is 


THE  SENSES 


227 


Papillae  with  taste,  buds 


covered  with  a  whitish  or  yellowish  coating,  or  when  it 
is  bright  red,  the  physician  knows  that  something  is 
wrong. 

If  we  examine  the  tongue  carefully,  we  find  that  it 
appears  much  as  in  Figure  77.  It  is  covered  with 
numerous  little  bunches 
or  papillae,  which  differ 
in  appearance  and  vary 
in  use.  Some  of  them, 
particularly  those  at  the 
back  of  the  mouth,  are 
associated  with  the  sense 
of  taste  and  are  called 
taste  buds  (see  Fig.  77). 
The  tongue  itself  is 
made  up  principally  of 
muscles,  which  run  in 
many  directions  and 
enable  us  to  move  the 
tongue  very  easily.  In 
addition  to  the  muscles 

there  are  glands  which  secrete  a  watery  material  that 
keeps  the  tongue  moist.  There  are  also  many  blood 
vessels  and  nerves,  among  them  some  which  are 
particularly  connected  with  taste,  and  which  carry  to 
the  brain  the  messages  that  enable  us  to  determine  the 
presence  of  sweet,  sour,  or  bitter  substances  ^in  the 
mouth. 

Tastes.  —  We  think  of   the  substances   that  we  eat 
as  having  many  different  tastes.     All  kinds  of  tastes 


FIG.  77.  —  THE  TONGUE. 
Showing  the  papillae  on  its  surface. 


228  PHYSIOLOGY  AND  HYGIENE 

may,  however,  be  classified  under  four  heads,  —  bitter, 
sweet,  acid  (sour),  and  salt.  These  different  tastes  are 
not  perceived  equally  well  in  all  parts  of  the  mouth. 
We  taste  sweet  things  most  delicately  at  the  tip  of 
the  tongue,  and  bitter  things  at  the  back  part  of  the 
mouth.  We  are  very  apt  to  confuse  tastes  and  smells, 
and  many  sensations  that  we  call  tastes  are  really 
tastes  and  smells  combined.  When  we  drink  a  glass  of 
soda  water,  for  example,  we  have  the  sweet  taste  of  the 
sirup,  but  the  gases  from  the  soda  water  pass  into  the 
nose  and  produce  a  very  strong  sense  of  smell.  The 
two  together  are  what  we  call  the  pleasant  taste  of 
the  soda  water.  Many  other  so-called  tastes  are  largely 
smells,  as  can  be  tested  by  blindfolding  a  person,  hold- 
ing his  nose  so  that  he  cannot  catch  the  odor,  and  then 
giving  him  successively  small  pieces  of  apple,  onion, 
and  potato. 

Duration  of  the  Sense  of  Taste.  —  Our  sense  of  light 
is  gone  at  almost  the  instant  the  light  ceases  to  shine 
into  the  eye,  and  the  sense  of  sound  stops  as  soon  as  the 
vibration  that  produces  it  ceases  or  becomes  too  distant 
to  affect  the  ear.  The  sense  of  taste,  however,  does 
not  cease  so  quickly,  but  it  may  last  many  seconds,  or 
even  several  minutes,  after  the  substance  tasted  has 
been  swallowed,  partly  because  some  of  the  substance 
remains  in  the  mouth.  An  unusually  bitter  taste,  like 
that  of  quinine,  may  last  as  long  as  half  an  hour. 

The  sense  of  taste  easily  becomes  tired,  and  in  this 
respect  it  is  quite  different  from  the  sense  of  sight.  We 
may  use  our  eyes  all  day  long,  and  yet  see  as  clearly  at 


THE   SENSES  229 

night  as  in  the  morning.  But,  if  we  continue  to  use  our 
sense  of  taste  for  even  a  few  minutes,  it  loses  its  acute- 
ness.  We  can  test  this  characteristic  by  eating  a  lemon. 
Food  does  not  have  so  pleasant  a  taste  at  the  close  of  a 
meal  as  at  its  beginning,  so  we  often  finish  our  dinner 
with  a  highly  flavored  dessert  to  please  our  taste,  which 
has  by  this  time  become  dull. 

Our  sense  of  taste  is  one  of  our  greatest  enjoyments, 
but  to  obtain  the  most  pleasure  from  it  we  must  not 
gratify  it  too  much.  If  we  live  upon  plain  food,  with 
an  occasional  luxury,  we  shall  find  more  enjoyment  in 
it  than  do  people  who  are  constantly  eating  highly 
flavored  foods.  The  luxury  gives  special  pleasure  only 
when  it  is  unusual.  If  we  should  eat  the  most  delicious 
food  constantly,  it  would  soon  come  to  give  us  less 
enjoyment.  The  bulk  of  our  food  should  be  such  as 
satisfies  the  appetite  rather  than  the  taste.  Finely 
flavored  substances,  like  candies,  sauces,  and  sweets  in 
general,  should  be  used  in  comparatively  small  quanti- 
ties, if  we  wish  to  enjoy  them  as  much  as  possible. 

THE  SENSE  OF  SMELL 

The  sense  of  smell  enables  us  to  determine  the  pres- 
ence of  certain  gases.  Only  substances  that  are  in  the 
form  of  a  gas _ox- vapor. can  be  smelled.  Rose  water  is  a 
liquid,  but  the  only  part  that  we  smell  is  the  vapor  that 
rises  from  it.  The  amount  of  vapor  required  to  excite 
the  sense  of  smell  is  exceedingly  minute.  If  a  bottle  of 
peppermint  oil  be  opened  for  a  few  moments,  it  will  give 
off  a  vapor  that  will  fill  the  room  and  will  be  smelled 


230 


PHYSIOLOGY  AND   HYGIENE 


Olfactory 
Nerves 


by  every  one  present.  Yet  if  the  bottle  of  liquid  be 
weighed  in  the  most  delicate  scales,  there  will  be  no 
perceptible  difference  in  the  weight  before  and  after  the 
bottle  was  opened.  No  other  sense  is  as  delicate  as  that 
of  smell. 

Location.  —  The  sense  of  smell  is  located  in  the  cavities 
of  the  nose.  The  two  nostrils  lead  into  two  large  cavi- 
ties above  the  mouth, 
separated  from  each 
other  by  a  bony  parti- 
tion. The  cavities 
extend  backward  to 
the  throat.  They  are 
partly  filled  with  large, 
thin,  folded  bones, 
which  bend  around  so 
as  to  form  curved  sur- 
faces. They  give  a 
large  amount  of  ex- 
posure to  the  air,  as  it 
passes  over  them. 
Upon  these  bones  are  the  nerves  of  smell  (olfactory 
nerves),  as  shown  in  Figure  78.  Vapors  entering  the 
nose,  as  we  breathe,  act  upon  these  nerves  in  such  a 
way  that  they  send  messages  to  the  brain,  and  produce 
in  the  brain  the  sensation  that  we  call  odor  or  smell. 

Its  Use.  —  The  sense  of  smell  in  human  beings  is  not 
so  well  developed  as  in  some  animals,  or  so  useful.  We 
may  occasionally  notice  by  its  aid  the  presence  of  inju- 
rious gases,  such  as  illuminating  gas  which  is  escaping 


FIG.  78. — A  VERTICAL  SECTION  OF  THE 

NOSE. 
Showing  the  nerves  of  smell. 


THE   SENSES  231 

from  a  burner.  Sometimes,  also,  we  perceive  through 
the  sense  of  smell  the  presence  of  some  body  or  substance 
which  gives  off  a  special  odor,  but  which  is  concealed 
from  our  eyes.  With  some  animals  the  sense  of  smell 
is  much  more  keen  than  it  is  with  human  beings.  A 
dog  can  follow  his  master's  footsteps  by  means  of  his 
very  keen  sense  of  smell. 

The  acuteness  of  the  sense  of  smell  is  blunted  by  con- 
tinued use  even  more  than  is  that  of  taste,  as  we  can 
readily  prove  with  cologne  or  other  strong  odor.  The 
first  whiff  of  cologne  on  a  handkerchief  gives  a  strong 
sensation.  If,  however,  we  bury  our  face  in  the  hand- 
kerchief and  continue  to  breathe  the  odor,  we  cease  to 
smell  the  cologne.  It  order  to  perceive  it  again,  we 
must  remove  the  handkerchief  from  the  nose  and  let 
the  smelling  organs  rest  for  a  time. 

OTHER  SENSATIONS 

We  frequently  say  we  have  five  senses,  —  seeing,  hear- 
ing, tasting,  smelling,  and  feeling.  The  first  four  of  these 
are  quite  distinct.  The  fifth,  which  we  call  feeling,  is 
made  up  of  several  different  kinds  of  sensations.  There 
are  really  two  different  senses  in  the  skin,  —  touch 
and  temperature.  In  addition  to  these  the  term  feeling 
usually  covers  the  pain  sense,  hunger,  thirst,  and  some 
other  sensations. 

The  Touch  or  Pressure  Sense.  —  The  skin  is  sensitive 
to  the  touch  or  pressure  of  objects.  Whenever  a  sub- 
stance presses  even  very  lightly  upon  the  skin  it  excites 
the  nerves  in  such  a  way  that  nervous  impulses  are 


232  PHYSIOLOGY  AND  HYGIENE 

sent  to  the  brain,  which  builds  out  of  these  impulses  an 
impression,  more  or  less  distinct,  of  the  object  that 
touched  us.  We  can  easily  test  this  by  shutting  our 
eyes  and  letting  some  one  touch  us  with  different  kinds 
of  unknown  objects.  The  whole  skin  is  thus  an  organ 
of  touch,  although  it  is  more  sensitive  in  some  places 
than  in  others. 

Through  the  messages  that  come  to  the  brain  from 
the  skin  we  not  only  get  a  sensation  that  the  skin  is 
touched,  and  that  the  object  touching  it  causes  a  cer- 
tain amount  of  pressure,  but  we  know  quite  accurately 
what  part  of  the  body  is  in  contact  with  the  object. 
We  can  tell  whether  the  ring  is  on  the  finger  or  is  lying 
on  the  palm  of  the  hand,  and  whether  it  is  on  the  little 
finger  or  the  thumb.  The  delicacy  with  which  we  can 
determine  where  the  skin  is  touched  differs  very  much 
on  different  parts  of  the  body,  as  can  be  easily  discov- 
ered by  experiment.  It  is  most  delicate  at  the  tips  of 
the  fingers  and  the  tip  of  the  tongue.  We  can  tell 
within  a  twenty-fifth  of  an  inch  where  an  object,  like  a 
needle  point,  touches  the  skin  of  the  finger  tips  or  the 
tongue.  The  sense  of  location  is  much  less  delicate  on 
the  back  of  the  fingers,  and  still  less  so  on  various  parts 
of  the  arms  and  shoulders.  Upon  the  back  of  the  shoul- 
ders it  is  least  delicate  of  all ;  in  fact,  we  cannot  deter- 
mine within  two  and  a  half  inches  where  an  object 
touches  the  back  part  of  the  shoulder.  We  can  see 
from  this  that  the  parts  of  the  body  most  used  are  the 
ones  in  which  the  sense  of  touch  is  the  most  delicate. 

It  is  the   sense   of  touch,  or  of  location   of  touch 


THE   SENSES 

sensations,  that  gives  us  our  most  intimate  knowledge 
of  the  nature  of  objects  outside  our  bodies.  By  the 
sense  of  touch  alone  we  can  tell  whether  such  objects 
are  rough  or  smooth,  whether  they  are  blunt  or  sharp, 
whether  they  are  solid  or  liquid. 

The  Temperature  Sense.  — When  a  warm  body  touches 
the  skin,  nervous  impulses  go  to  the  brain,  and  we  have 
a  feeling  of  warmth.  The  skin,  in  general,  is  sensitive 
to  both  cold  and  heat,  though  some  points  on  the  skin 
are  sensitive  to  heat  and  not  to  cold,  while  others  are 
sensitive  to  cold  and  not  to  heat.  The  warm  and 
cold  spots  are  very  close  together,  so  that  a  body  no 
larger  than  the  head  of  a  pin  will  in  some  places  touch 
both.  Every  part  of  the  body  has  a  certain  tem- 
perature, and  if  some  object  warmed  to  that  exact 
temperature  touches  the  skin,  the  pressure  of  the  object 
will  be  felt,  but  it  will  seem  to  be  neither  warm  nor 
cold.  If,  however,  the  object  is  a  little  warmer  than 
is  the  skin  at  the  point  where  it  touches,  it  will  seem 
warm  ;  if  it  is  a  little  cooler  than  the  skin  at  that 
point,  it  will  seem  cold.  The  temperature  of  the 
skin  is  not  just  the  same  on  all  parts  of  the  body. 
The  temperature  of  the  hand  is  usually  a  little  lower 
than  that  of  the  forehead,  so  that  an  object  which  feels 
warm  to  the  hand  may  feel  cool  to  the  forehead.  The 
forehead  itself  feels  warm  to  the  hand. 

If  we  step  in  cold  weather  from  a  carpet  to  a  bare 
floor,  the  floor  feels  colder  to  the  feet  than  the  carpet, 
although  the  two  are  actually  of  the  same  temperature. 
The  bare  floor  draws  the  heat  away  from  the  feet  more 


234  PHYSIOLOGY  AND  HYGIENE 

rapidly  than  the  carpet  does.  Any  object  feels  cool 
when  it  takes  heat  away  from  the  body  rapidly.  If  it 
withdraws  no  heat  from  the  body,  we  feel  that  the 
object  touches  the  skin,  but  we  feel  no  sensation  of  cold 
resulting  from  the  contact.  Some  substances  draw  heat 
more  rapidly  than  others,  and  this  is  why,  in  cold 
weather,  for  example,  metal  objects  seem  colder  than 
cloth  to  the  touch. 

Sense  of  Pain.  —  Almost  any  nerve  which  carries  mes- 
sages to  the  brain  will  carry  a  sense  of  pain,  if  it  is 
strongly  excited.  If  the  pain  is  slight,  we  can  deter- 
mine very  closely  where  it  comes  from;  but  if  it  is 
severe,  we  cannot  locate  it  so  accurately.  A  slight 
toothache,  for  example,  can  be  located  in  the  proper 
tooth,  but  when  it  is  severe,  it  seems  to  come  from  the 
entire  jaw,  or  the  whole  side  of  the  head.  Occasionally 
the  whole  upper  part  of  the  body  appears  to  be  in  pain, 
although  the  trouble  is  confined  to  a  single  tooth. 

We  find  it  hard  to  realize  that  pain  is  of  any  use,  but 
it  really  is  of  great  value.  If  it  did  not  hurt  to  burn 
the  fingers,  children  would  get  their  fingers  so  badly 
burned  as  to  render  them  useless.  In  fact,  they  would 
probably  destroy  the  fingers  entirely  before  they  were 
old  enough  to  know  how  to  take  care  of  themselves. 
Pain  thus  warns  us  to  guard  our  bodies  from  accidents 
and  disease,  and  to  keep  them  in  as  good  a  condition  as 
possible.  Pain  is  a  warning  to  our  bodies,  and  we  should 
heed  it  as  carefully  as  does  the  engineer  the  danger 
signal  beside  the  railroad  track. 


THE  SENSES  235 

The  Muscle  Sense.  —  We  seldom  hear  any  one  speak 
of  the  muscle  sense,  but  it  is  really  of  considerable  im- 
portance. It  is  the  sense  by  which  we  know  when  and 
how  much  we  contract  our  muscles.  Even  when  we 
shut  our  eyes  we  can  move  our  fingers  very  accurately, 
knowing  almost  exactly  how  much  the  muscles  contract. 
Let  us  say,  for  example,  that  we  will  allow  one  hand  to 
rest  upon  the  table  while  we  close  our  eyes.  If,  while 
our  eyes  are  still  closed,  another  person  lifts  the  hand, 
we  can  tell  very  accurately  by  means  of  the  muscle 
sense  how  far  it  has  been  lifted.  This  sense  is  of  great 
importance,  for  it  enables  us  to  control  our  actions  and 
to  move  our  muscles  together.  If  we  could  not  feel 
how  much  we  move  the  muscles,  we  could  not  possibly 
make  the  body  motions  that  require  the  contraction  of 
a  number  of  muscles  at  the  same  time,  as  when  we 
throw  a  stone.  The  muscle  sense  is  not  situated  in 
any  particular  place,  but  is  present  in  all  parts  of  the 
body,  especially  in  the  joints. 

QUESTIONS 

1.  How  does  the  brain  get  a  knowledge  of  the  world? 

2.  What  are  the  chief  sense  organs  ? 

3.  What  is  the  shape  of  the  eyeball,  and  where  is  it  located? 

4.  What  are  the  eyelids ?    What  is  their  purpose? 

5.  Where  are  the  tear  glands  located?    What  is  their  use? 

6.  How  are  the  eyeballs  moved  ? 

7.  What  are  the  principal  parts  of  the  eye? 

8.  Why  is  it  desirable  to  sit  erect  when  reading? 

9.  If  the  lens  of  the  eye  should  become  opaque,  what  would  be 
the  result? 


236  PHYSIOLOGY  AND   HYGIENE 

10.  Some  persons  cannot  distinguish  between  green  and  ripe 
cherries.     Can  you  explain  the  reason? 

11.  In  what  five  ways  should  we  care  for  the  eyes? 

12.  Where  are  the  real  hearing  organs  ? 

13.  What  are  the  important  parts  of  the  ear? 

14.  How  do  the  ears  enable  us  to  hear  ? 

15.  How  should  we  care  for  the  ears? 

16.  If  two  colors  are  mixed,  do  we  get  a  new  color?    If  two 
sounds  are  mixed,  do  we  get  a  new  sound  or  do  we  hear  both 
sounds  ? 

17.  If  you  close  the  nose  and  swallow,  what  effect  is  produced 
in  the  ears?    Can  you  explain  why  ? 

18.  Where  is  the  sense  of  taste  located? 

19.  What  is  the  structure  of  the  tongue  ? 

20.  Mention  several  duties  of  the  tongue? 

21.  What  may  be  said  of  the  duration  of  the  sense  of  taste? 

22.  Where  is  the  sense  of  smell  located  ?    How  may  this  sense 
be  dulled? 

23.  How  could  you  tell  whether  soda  water,  without  sirup,  has 
a  taste  or  only  a  smell  ? 

24.  What  three  sensations  compose  the  sense  of  feeling? 

25.  What  is  the  use  of  the  touch  or  pressure  sense  ? 

26.  What  do  we  learn  from  the  sense  of  heat  and  cold  ? 

27.  Lay  the  palm  of  the  hand  upon  the  cheek.     Does  the  hand 
appear  warm  or  cool  ?    Do  the  same  upon  the  forehead.    What  do 
you  observe? 

28.  Of  what  use  is  pain  ?  . 

29.  Of  what  importance  is  the  muscle  sense  ? 


CHAPTER  XIII 
HEALTH   AND  DISEASE 

THE  body  is  a  very  delicate  piece  of  machinery,  as  we 
can  readily  appreciate.  It  needs  to  be  treated  carefully, 
but  most  of  us  have  bodies  that  will  keep  in  good 
condition  if  we  care  for  them  properly. 

The  Body  cures  Most  of  its  Own  Ills.  —  The  human 
body  is  such  a  beautifully  constructed  machine  that  it 
will  of  itself  take  care  of  the  ordinary  slight  illnesses. 
If  we  have  a  cold,  the  body  soon  cures  it ;  wounds  are 
rapidly  healed;  broken  bones  are  mended;  digestive 
troubles'  usually  disappear.  All  of  these  little  maladies 
the  body  itself  can  care  for.  We  need  simply  to  do 
our  part  toward  keeping  in  good  condition  by  eating 
plain,  wholesome  food,  taking  plenty  of  exercise,  and 
living  as  much  as  possible  out  of  doors  in  the  fresh  air 
and  sunshine. 

Many  people  have  the  idea  that  the  proper  way  to 
treat  ailments  of  all  sorts  is  to  take  medicines.  This  is 
a  great  mistake.  Medicines  cannot  cure  disease.  The 
most  they  can  do  is  to  aid  the  body  to  right  itself. 
Most  people  would  be  better  off  by  letting  nature  cure 
their  little  ailments,  giving  her  the  aid  that  comes  from 
such  simple  remedies  as  baths,  soaking  the  feet  in  hot 
water,  and  rubbing,  rather  than  by  dosing  themselves 

237 


238  PHYSIOLOGY    AND   HYGIENE 

with  drugs.  Medicines  should  be  used  only  under  a 
physician's  guidance.  The  constant  use  of  drugs  rather 
weakens  than  strengthens  the  general  physical  powers. 
If  people  used  fewer  drugs  and  more  common  sense, 
took  less  medicine  and  more  exercise,  wore  fewer  wraps 
in  winter  and  spent  more  time  out  of  doors,  we  should 
hear  less  about  sickness,  and  the  whole  race  would  be 
more  robust. 

Disease.  —  When  the  machinery  of  the  body  is  out  of 
order  we  speak  of  the  condition  as  sickness  or  disease. 
The  causes  of  diseases  are  numerous.  Sometimes  they 
are  the  result  of  improper  food  habits,  or  intemperance, 
of  breathing  impure  air,  or  of  other  improper  conditions 
of  life.  One  class  of  very  important  diseases  is  pro- 
duced by  parasitic  animals  or  plants  growing  in  the 
body. 

Some  diseases  we  say  are  "  catching,"  by  which  we 
mean  that  one  person  very  readily  gets  the  disease  from 
another.  This  class  includes  such  diseases  as  measles, 
scarlet  fever,  mumps,  whooping  cough,  etc.  Such  dis- 
eases are  called  contagious.  Another  class  of  troubles, 
like  rheumatism,  malaria,  etc.,  are  non-contagious,  since 
healthy  persons  do  not  "  catch  "  them  from  sick  people. 

PARASITIC  DISEASES 

Contagious  diseases  are  probably  all  caused  by  very 
small  animals  or  plants  that  get  into  the  human  body 
and  multiply  there.  Most  of  them  are  so  small  that 
they  can  be  seen  only  with  the  aid  of  a  very  powerful 
microscope. 


HEALTH  AND   DISEASE  239 

Parasitic  Animals.  —  There  are  a  few  animal  parasites 
that  occasionally  get  into  our  bodies  and  cause  trouble. 
One  of  these  is  the  tapeworm,  which  enters  the  body 
from  raw  or  insufficiently  cooked  beef  or  pork.  It  lives 
in  the  intestines  and  makes  considerable  trouble,  al- 
though it  is  not  usually  very  dangerous.  Another  such 
parasitic  animal  is  the  trichina,  which  also  comes  from 
eating  pork,  not  properly  cooked,  such  as  rare  or 
slightly  cooked  ham  or  sausage.  The  disease  resulting 
is  violent  and  painful,  and  often  causes  death.  The 
simple  method  of  avoiding  both  tapeworm  and  trichina 
is  to  eat  no  meat  that  is  not  thoroughly  cooked. 

Another  form  of  animal  parasite  produces  malaria,  or 
chills  and  fever.  This  parasite  is  a  minute  animal,  to 
be  seen  only  through  a  microscope,  which  gets  into  the 
body,  usually  from  the  bite  of  the  mosquitOo  Certain 
kinds  of  mosquitoes  are  liable,  when  they  bite,  to  leave 
in  the  skin  some  of  these  little  parasites.  The  best 
way  to  protect  ourselves  against  malaria  or  chills  and 
fever  is  to  keep  from  being  bitten  by  mosquitoes. 
This  may  be  done  generally  by  covering  the  doors  and 
windows  of  our  houses  with  mosquito  netting,  particu- 
lar care  being  taken  to  remain  behind  such  netting  at 
night. 

Parasite  Bacteria.  —  The  most  important  of  the  para- 
sites that  make  their  way  into  the  body  are  a  type  of 
plant  called  bacteria.  These  minute  plants  are  so  small 
that  a  powerful  microscope  is  required  to  see  them,  and 
so  light  that  they  can  easily  float  around  in  the  air  in 
the  form  of  dust.  They  are  very  abundant  everywhere. 


240 


PHYSIOLOGY  AND  HYGIENE 


Some  of  them,  instead  of  being  harmful,  are  directly 
useful  to  us.  Bacteria  cause  the  souring  of  milk  and 
the  decay  of  meat ;  they  produce  vinegar  and  the  flavor 
of  butter  and  cheese;  and  they  prepare  the  soil  for  the 
growth  of  plants.  These  tiny  parasites  are,  on  the 
whole,  very  useful  friends  of  ours. 

But  while  some  bacteria  are  healthful,  others,  which 
may  live  as  parasites  in  our  bodies,  produce   certain 

,  i  diseases.    Some  of  these 

/•  i 
1'X  are    shown    in    Figure 

/f         J s  ^      79.     Typhoid  fever,  con- 

1 1/     Cholera         rfifri      sumption  (tuberculosis), 

Tubercu/os/s 
Typhoid 


000 


0000° 
Abscess 

FIG.  79.  —  BACTERIA  THAT  PRODUCE 
CERTAIN  DISEASES. 


Other  contagious  dis- 
eases, like  measles,  scar- 
let fever,  mumps,  and 
whooping  cough,  are 
probably  caused  either 
by  bacteria  or  by  some 
other  microscopic  parasites.  Each  of  the  different  dis- 
eases is  produced  by  its  own  kind  of  bacteria. 

Protection  against  Harmful  Bacteria.  —  Bacteria  can- 
not ordinarily  injure  us  unless  they  get  inside  the  body. 
We  have  already  seen  how  the  skin  forms  a  covering 
which  protects  the  body  from  the  entrance  of  external 
objects,  and  this  commonly  keeps  out  dangerous  bac- 
teria. So  well  are  we  protected  that  the  majority  of 
them  do  no  harm  whatever,  because  they  do  not  obtain 


HEALTH  AND  DISEASE  241 

entrance  to  the  body.  We  need  not  be  frightened, 
then,  because  bacteria  are  present  in  milk  and  water, 
for  this  is  the  natural  condition.  The  bacteria  in  milk, 
and  also  those  in  water,  are  usually,  though  not  always, 
harmless. 

Even  if  the  bacteria  of  diseases  do  find  their  way  into 
the  body,  it  does  not  necessarily  follow  that  they  will 
effect  injury.  The  human  body  is  able  to  fight  these 
bacteria,  and  in  many  cases  to  destroy  them  before  they 
do  harm.  When  we  are  in  the  best  condition  of  health, 
our  power  of  resisting  them  is  greatest,  and  conse- 
quently we  are  then  less  liable  to  take  some  contagious 
diseases  than  when  we  are  in  a  more  or  less  weakened 
state.  In,  general,  the  best  method  of  avoiding  all  bac- 
terial diseases  is  to  keep  in  robust  health,  although 
even  perfect  health  apparently  cannot  protect  one 
against  taking  some  contagious  diseases.  Robust 
health,  as  we  have  seen,  depends  upon  plain,  whole- 
some food,  plenty  of  fresh  air  and  outdoor  exercise, 
and  living  a  regular  life. 

Immunity  from  Contagious  Diseases.  —  Many  conta- 
gious diseases,  such  as  smallpox,  scarlet  fever,  mumps, 
chicken  pox  and  yellow  fever,  are  rarely  taken  by  the 
same  person  more  than  once.  In  some  way,  which  we 
do  not  fully  understand,  the  first  attack  acts  upon  the 
body  so  that  it  is  able  to  resist  the  action  of  the  para- 
sites ever  afterward.  A  person  who  has  had  one  attack 
of  such  a  disease  is  said  to  be  immune  to  future  attacks. 
Advantage  is  taken  of  this  fact  by  vaccination,  by  which 
we  are  protected  against  smallpox.  When  vaccination 


242  PHYSIOLOGY  AND  HYGIENE 

"  takes,"  it  causes  what  is  really  much  like  a  mild  form 
of  smallpox,  which  makes  us  for  a  certain  time  immune 
to  that  disease. 

Prevention  of  Contagious  Disease.  —  The  best  way  to 
check  the  spread  of  contagious  diseases  is  to  prevent 
the  distribution  of  the  bacteria  that  cause  them.  If  we 
can  keep  these  minute  growths  from  passing  from  one 
person  to  another,  we  can  frequently  stay  the  spread  of 
the  disease.  The  rules  adopted  by  the  boards  of  health 
in  our  cities,  especially  in  connection  with  schools,  are 
made  for  the  sake  of  preventing  the  spread  of  bacteria. 
That  is  why  persons  having  contagious  diseases,  such 
as  diphtheria,  are  placed  in  rooms  by  themselves.  That 
is  why  children  are  not  allowed  to  attend  school  when, 
for  example,  a  member  of  the  family  has  the  measles. 
In  general,  the  regulation  of  these  matters  may  be  left 
to  boards  of  health,  but  there  are  a  few  facts  which  it 
is  well  for  us  all  to  understand. 

How  Bacteria  get  out  of  the  Body.  —  When  a  conta- 
gious disease  is  "taken"  from  a  person  by  another, 
the  bacteria  which  produce  the  disease  must  have 
passed  from  the  body  of  the  patient  to  that  of  the  other 
individual.  Usually,  the  bacteria  pass  from  the  body 
of  the  sick  person  in  some  of  the  secretions  or  excre- 
tions. If  the  disease  is  accompanied  by  sores,  such 
as  boils,  the  bacteria  leave  the  body  in  the  discharges 
from  the  sores.  If  there  is  an  eruption  from  the 
skin,  as  in  scarlet  fever  and  measles,  the  bacteria  prob- 
ably leave  the  body  from  the  skin,  as  well  as  from  the 
discharges  of  the  mouth  and  nose.  If  there  is  a  dis- 


HEALTH  AND   DISEASE  243 

charge  from  the  digestive  canal,  as  in  typhoid  fever, 
bacteria  find  exit  with  what  passes  from  the  bowels.  If 
the  disease  is  in  the  mouth  or  throat,  as  in  diphtheria, 
bacteria  will  usually  be  found  in  the  saliva.  If  it  is 
in  the  lungs,  as  in  consumption,  we  may  look  for  the 
bacteria  in  the  saliva  and  phlegm  coughed  up  by  the 
patient.  If  the  disease  is  accompanied  by  a  cough,  as  in 
whooping  cough,  we  may  regard  the  breath  during  the 
coughing  as  carrying  the  bacteria. 

How  Bacteria  are  Carried.  —  1.  Many  of  the  dis- 
charges from  patients  get  into  sewage  through  drains 
and  closets.  Hence  the  sewage  of  a  city  is  almost  sure 
to  contain  hosts  of  dangerous  bacteria,  and  it  should 
be  disposed  of  in  the  safest  and  most  careful  manner 
possible.  If  it  enters  a  river,  and  the  water  of  the 
same  river  is  used  for  drinking,  many  cases  of  typhoid 
fever  are  almost  sure  to  arise.  Most  of  the  sewage  of 
a  city  enters  into  common  sewers,  and  each  house  is 
connected  with  these  sewers.  It  is  necessary,  there- 
fore, to  have  means  for  preventing  the  bacteria  in  the 
sewers  from  entering  the  house.  .This  is  accomplished 
by  properly  devised  plumbing.  We  can  thus  compre- 
hend the  importance  of  having  and  keeping  the 
plumbing  of  a  house  in  good  condition. 

2.  Bacteria  may  be  transferred  by  contact,  either 
actual  contact  with  a  patient  or  with  something  that 
he  has  touched.  A  nurse  may  get  bacteria  upon  her 
hands  from  handling  the  patient  or  his  clothing.  If 
she  washes  her  hands  frequently  and  refrains  from  put- 
ting her  fingers  to  her  mouth,  the  danger  from  conta- 


244  PHYSIOLOGY  AND  HYGIENE 

gion  will  be  largely  reduced.  Other  persons  in  the 
house  may  take  a  contagious  disease  by  using  spoons, 
knives,  forks,  cups,  or  saucers  which  have  been  em- 
ployed in  the  sick  room.  Bacteria  cling  to  such  arti- 
cles, and  may  thus  be  transferred  to  any  person  using 
the  dishes.  The  danger  may  be  avoided  by  allowing 
no  one  to  use  the  same  eating  utensils  as  the  sick  per- 
son, or  by  washing  them  thoroughly  in  boiling  water 
before  they  are  used  by  others.  Bacteria  are  also  fre- 
quently left  by  sick  persons  upon  door  knobs,  stair 
rails,  etc.,  and  these  should,  therefore,  be  carefully 
washed.  In  general,  it  is  an  excellent  rule  always  to 
wash  the  hands  before  eating,  and  to  avoid  eating  food 
which  has  been  handled  by  others. 

3.  Bacteria  may  be  carried  by  the  air.  When  the 
skin  peels,  as  in  scarlet  fever,  or  when  there  is  a  skin 
eruption,  as  in  smallpox,  the  germs  probably  pass  into 
the  air,  and  may  thus  be  carried  to  other  persons.  The 
same  is  true  of  diseases  with  which  there  is  a  cough, 
such  as  whooping  cough  and  consumption.  It  is  not 
very  easy  to  guard  against  this  danger  if  we  must  stay 
in  the  same  room  with  the  patient ;  but  the  danger  may 
be  reduced,  as  much  as  this  is  possible,  by  insisting 
upon  a  constant  supply  of  fresh  air  in  the  sick  room. 
The  germs,  after  floating  in  the  air  for  a  while,  settle 
with  the  dust.  Every  time  the  room  is  swept  or  dusted 
they  are  stirred  up  again.  Sweeping  and  dusting 
schoolrooms  increases  the  chance  of  the  spread  of  con- 
cagious  diseases.  So  far  as  possible,  wiping  with  damp 
cloths  should  replace  sweeping  and  dusting.  *  After  the 


HEALTH  AND  DISEASE  245 

bacteria  have  reached  the  out-of-door  air,  most  of  them 
are  killed  by  the  sunshine,  although  this  is  not  true  of 
the  bacteria  of  all  diseases. 

4.  Uncooked  food  sometimes  distributes  disease  bac- 
teria.    This  applies  chiefly  to  water  and  milk.    Water 
from  a  river  receiving  city  sewage  is  the  most  common 
source  of  typhoid  fever.    Milk  is  occasionally  the  source 
of  diphtheria,  scarlet  fever,  typhoid  fever,  or  diarrhoea. 
In  case  of  epidemics  from  water,  we  may  protect  our- 
selves by  having  the  water  boiled  before  we  drink  it. 
The  only  protection  against  disease  carried  by  milk  is 
either  to  buy  the  milk  from  reliable  sources  or  to  boil 
it   before  it  is  used.     Other  foods  which  we  eat  un- 
cooked, such  as  lettuce,  celery,  raw  oysters,  and  fruit, 
are   occasionally   sources   of   disease.      Cooking  is  an 
efficient  safeguard  against  the  danger. 

5.  Occasionally   flies    or   other    insects    may   carry 
disease   germs,  particularly  those  of  cholera,  typhoid 
fever,  and  some  eye  diseases.     The  chief  precaution  to 
be  taken  is,  as  far  as  possible,  to  prevent  flies  from 
alighting  on  our  food  or  eating  utensils.     We   have 
already   learned    that    mosquitoes   distribute    malaria, 
and  it  is  also  true  that  they  carry  yellow  fever. 

Every  one  should  bear  in  mind  a  few  simple  rules 
which,  if  followed,  will  help  to  prevent  the  spread  of 
contagious  diseases.  They  are  particularly  important 
in  schools  where  children  from  many  families  are 
brought  together. 

-Do  not  spit  on  the  floor  or  sidewalk. 

Do  not  put  pencils  or  penholders  into  the  mouth. 


246  PHYSIOLOGY   AND   HYGIENE 

Do  not  put  the  fingers  in  the  mouth. 

Do  not  put  money  in  the  mouth. 

Never  put  into  the  mouth  anything  that  another  per- 
son has  had  in  his  mouth  (gum,  bean  blowers,  whistles, 
drinking  cups,  etc.). 

When  coughing  turn  the  face  away  from  others,  and 
avoid  allowing  others  to  cough  in  your  face. 

Wash  the  face  and  hands  often. 

By  these  means  we  may  largely  avoid  the  germs 
which  might  get  into  our  bodies. 

THE  USE  OF  ALCOHOL 

We  have  learned  in  previous  pages  that  alcoholic  bev- 
erages are  quite  unnecessary  to  health,  and  are  in  many 
cases  extremely  harmful.  They  interfere  to  a  large 
extent  with  the  perfect  health  and  happiness  of  man- 
kind. The  question  might  naturally  be  asked,  Why  is 
it  that  people  learn  to  use  alcoholic  beverages  when 
these  are  not  only  of  no  use,  but  liable  to  do  so  much 
injury  ?  There  are  three  main  reasons :  — 

(1)  The  boy  does  not  realize  the  risk  he  is  running. 
He  does  not  expect  that  he  will  become  addicted  to  the 
use  of  alcohol  in  such  a  way  as  to  injure  him.     Com- 
monly he  does  not  know  the  danger  that  lies  before  him, 

(2)  The   boy  sometimes  -knows   well   enough   that 
alcohol  is  dangerous  and  likely  to  do  him  harm,  bat 
he  thinks  it  manly  to  drink,  and  is  afraid  of  being  called 
odd  or  priggish  if  he  does  not.     But  it  is  not  manliness 
that   causes  a   boy   to   follow   his   companions   into   a 
saloon.    On  the  contrary,  it  is  usually  cowardice.     He 


HEALTH  AND   DISEASE  247 

is  afraid  that  he  may  be  laughed  at.  It  is  really  the 
manly  and  courageous  boy  who  dares  to  stay  outside 
and  to  refuse  to  follow  others  <*nto  useless  danger,  and 
in  the  end  his  associates  never  fail  to  recognize  and  to 
admire  his  real  courage  and  manliness. 

(3)  The  third  reason  is  the  desire  to  be  social.  The 
boy  finds  that  his  companions  drink  beer,  and  he  feels  it 
more  social  to  follow  their  lead,  even  at  the  cost  of  some 
danger  to  himself,  than  to  oppose  them,  especially  if  they 
are  a  little  older  than  he.  He  should  remember  that 
the  kind  of  sociability  that  leads  to  a  saloon,  or  into 
any  other  useless  danger,  had  better  be  shunned.  There 
is  companionship  far  pleasanter  than  that  which  comes 
through  a  glass  of  beer,  and  there  are  friends  more  use- 
ful than  those  who  invite  one  to  a  saloon  or  urge  one  to 
join  in  a  social  glass. 

Reasons  why  Alcohol  should  be  entirely  avoided  as  a 
Beverage.  —The  only  wise  course  is  to  let  alcohol  en- 
tirely alone.  There  are  three  important  reasons  for 
so  doing  :  — 

(1)  It  will  do  us  physical  harm.  It  is  impossible 
for  any  one  to  tell  where  the  injurious  effects  begin,  or 
to  say  how  much  he  may  use  without  harm  to  himself. 
Small  quantities  are  liable  to  lead  to  larger  ones,  and 
the  habit  of  using  alcohol,  is  apt  to  cause  an  appetite 
which  will  result  in  untold  evil.  The  only  safety  lies 
in  avoiding  alcoholic  beverages  altogether.  Many  a 
person  who  seemed  strong-willed  has  to  his  sorrow 
found  his  will  power  insufficient  to  resist  the  craving 
which  alcohol  has  developed. 


248  PHYSIOLOGY  AND  HYGIENE 

(2)  The  constant  use  of  alcohol,  even  in  moderate 
amounts,  frequently  lowers  one's  moral  tone  and  intelli- 
gence and  thus  interferes  with  one's  chance  of  success.   The 
parts  of  the  city  which  show  the  greatest  poverty  are 
the  parts  which  abound  in  saloons.     Prisons  are  filled 
with  men  and  women  who  have  used  alcohol.     The  use 
of  alcohol  not  only  means  the  waste  of  large  amounts 
of  money,  but  if  continued,  it  has  a  tendency  to  reduce 
a  person's  chance  in  life.     It  frequently  ruins  ambition ; 
it  tends  to  destroy  the  power  of  attending  strictly  to 
work;    it  makes   a   man   careless   about   fulfilling   his 
responsibilities,  and  is  likely  to  lead  to  loss  of  employ- 
ment.   Some  corporations,  especially  railroads,  refuse  to 
put  into  responsible  positions,  such  as  those  of  engineers 
and  switchmen,  persons  who  use  alcohol  even  "  in  mod- 
eration," or  occasionally.     It  is  not  simply  those  who 
use  alcohol  in  large  amounts  who  risk  their  chances 
of  filling  responsible  positions.     The  use  of  alcohol  is 
likely  to  bring  a  boy  into  a  circle  of  acquaintances  who 
will  injure  rather  than  benefit  him.     It  is  likely  also, 
when  he  has  become  a  man,  to  destroy  his  interest  in 
his  family  and  all  that  is  good,  and  to  lead  him  to  live 
a  life  upon  a  low  plane. 

(3)  Our  example  will  influence  others.     We  all  have 
some  responsibility  for   those   about   us,  and   to   lead 
another,  by  our  example,  into  a  course  of  life  that  in- 
jures him,  is  a  very  serious  thing,  the  results  of  which 
we  cannot  measure.     When  people  see  their  friends 
using  alcohol,  they  are  very  likely  to  think  that  they 
can  do  the  same.     They  may  be  led  to  use  alcohol  in 


HEALTH   AND  DISEASE  249 

excess  from  seeing  others  use  it  in  moderation.  The  mod- 
erate drinker  is  the  one  whom  others  try  to  follow.  He 
is  thus  in  a  measure  responsible  for  the  downfall  of  the 
friend  who,  weaker  than  himself,  tries  to  follow  his  lead. 
The  healthy  person  does  not  need  alcoholic  drinks 
and  is  better  off  without  them.  They  always  produce 
an  abnormal  mental  condition.  What  is  needed  for  the 
best  success  in  life  is  a  mind  acting  in  its  normal  con- 
dition and  uninfluenced  by  drugs,  either  by  narcotics  or 
stimulants.  Alcohol  always  makes  the  mind's  action 
unnatural  and  hence  inferior  to  its  natural  action.  This 
effect,  in  impairing  the  keenness  of  the  mental  action, 
is  just  as  sure  whether  small  or  large  amounts  are  used, 
though  differing  in  degree. 

THE  DUTY  OF  PRESERVING  HEALTH 

It  is  our  duty  to  make  the  most  of  our  opportunities 
in  life.  Whether  we  decide  upon  a  business  career  or 
a  profession,  we  are  sure  to  find  that,  in  the  sharp  com- 
petition of  to-day,  a  good  body  and  abundant  physi- 
cal health  are  wonderful  aids  in  reaching  the  greatest 
success  in  life.  Physical  strength  will  give  one  power 
to  become  a  leader  among  men.  Failure  to  develop 
our  powers  to  their  highest  extent  will  result  in  a  life 
unsatisfactory  to  ourselves.  It  is  our  duty  to  set  our 
ambitions  high.  There  is  no  one  who  may  not  hope 
for  success,  and  no  one  who  should  not  endeavor  to  live 
a  broad  and  useful  life.  The  higher  we  aim,  the  higher 
the  position  we  shall  reach.  It  is  perfectly  right  and 
honorable  to  determine  to  reach  a  responsible  position 


250  PHYSIOLOGY  AND  HYGIENE 

in  business,  to  acquire  wealth  and  power,  and  to  become 
a  person  of  influence.  These  things  are  possible  to 
every  American  youth  who  will  make  proper  use  of  his 
opportunities.  Without  perfect  health,  however,  suc- 
cess is  likely  to  slip  from  the  grasp.  One  of  the  best 
assurances  for  a  successful  life  is  a  well-developed, 
active,  healthful  body. 

We  should  remember  that  the  body  is  a  marvelous 
machine.  Its  value  depends  upon  its  being  in  a  condi- 
tion of  the  greatest  efficiency.  A  locomotive  with  a  leak- 
ing valve  may  still  pull  a  few  cars,  but  it  is  much  less 
useful  than  a  perfect  engine.  So  our  bodies,  even  when 
more  or  less  out  of  order  from  abuse  of  one  sort  or 
another,  may  still  keep  alive  and  carry  on  some  of  the 
duties  of  life;  but  they  will  do  less  work  than  when 
they  are  in  perfect  condition. 

The  value  of  the  human  body  as  a  machine  is  lowered 
by  every  form  of  overindulgence.  Excess  in  eating,  in 
talking,  in  playing,  or  in  working  reduces  our  chances 
of  future  success.  Immoderate  eating  and  drinking 
injure  digestion ;  excessive  talking  destroys  confidence 
in  our  statements ;  too  much  play  makes  a  boy  unready 
for  the  more  serious  duties  in  life ;  and  too  much  work 
makes  him  tired  and  dull.  The  study  of  our  body 
teaches  that  any  kind  of  indulgence  results  in  a  general 
lowering  of  the  powers  of  the  body  and  mind,  and  makes 
us  less  capable  of  achieving  the  highest  end  in  life. 

The  study  of  these  pages  has  resulted  in  showing 
that  two  great  fundamental  laws  for  developing  a 
perfect  body  and  living  a  useful  life  are  :  — 


OF 

§2^ 

HEALTH  AND  DISEASE  251 

(1)  Use  every  power  you  possess. 

(2)  Avoid  the  overindulgence  of  all  appetites  and  all 
desires. 

QUESTIONS 

1.  What  is  the  purpose  of  medicine  ? 

2.  Why  should  medicine  be  avoided  as  much  as  possible  ? 

3.  What  causes  most  contagious  diseases? 

4.  What  is  meant  by  parasitic  animals? 

5.  How  are  tapeworms  and  trichinae  taken  into  the  human  sys- 
tem ?    What  is  the  result  with  each  ? 

6.  How  are  malarial  organisms  taken  into  the  body? 

7.  How  can  the  body  best  be   protected   against   injurious 
bacteria? 

8.  How  may  the  spread  of  contagious  diseases  be  prevented? 

9.  How  do  the  injurious  bacteria  pass  from  a  person  who  has 
sores  or  boils?    Scarlet  fever  or  measles?    Typhoid  fever? 

10.  In  what  important  ways  may  bacteria  be  carried  ? 

11.  Why  should  plumbing  be  kept  in  good  condition? 

12.  How  may  bacteria  be  transferred  through  contact? 

13.  How  may  bacteria  be  carried  in  the  air? 

14.  Why  is  wiping  with  a  damp  cloth  better  than  dusting  in  a 
schoolroom  ? 

15.  How  may  bacteria  in  food  be  destroyed  ? 

16.  How  can  we  reduce  the  danger  of  taking  a  disease  dis- 
tributed by  coughing? 

17.  How  may  we  prevent  diseases  being  spread  by  insects  ? 

18.  Why  should  we  have  light  and  air  in  our  sleeping  rooms  ? 

19.  What  three  conditions  most  commonly  lead  a  person  to  use 
alcohol  as  a  beverage  ? 

20.  Why  should  alcohol  be  entirely  avoided  as  a  beverage  ? 

21.  What  are  the  two  fundamental  laws  of  health  and  use- 
fulness? 


'*-   9 


CHAPTER   XIV 
PREVENTABLE   DISEASES 

WE  have  learned  that  some  diseases  are  "  catching," 
or  contagious,  and  that  such  diseases  are  caused  by 
germs.  By  germs  we  mean  minute  living  animals  or 
plants,  far  too  small  to  be  seen  without  a  microscope, 
but  able  to  grow  and  multiply  inside  the  body  if  they 
once  get  in.  After  they  have  become  numerous  in  the 
body,  they  produce  trouble  that  we  call  disease.  If 
the  germs  get  outside  again  and  pass  into  the  body  of 
another  person,  they  may  produce  the  disease  in  him. 
For  this  reason  we  say  that  such  a  disease  is  contagious. 
A  contagious  disease  is  thus  simply  one  that  is  caused 
by  a  living  germ  which  is  easily  able  to  pass  from  a 
sick  person  to  a  healthy  one. 

GERM  DISEASES  ARE   PREVENTABLE 

People  used  to  think  of  diseases  as  mysterious  afflic- 
tions, sent,  perhaps,  by  some  angry  demon.  As  long 
as  they  were  thought  of  in  this  way,  it  was  impossible 
to  do  anything  to  prevent  them.  But  now  that  we 
know  that  diseases  are  caused  by  germs,  know  where 
the  germs  come  from,  how  they  are  carried  from  the 
sick  person,  and  how  they  get  into  the  well  person,  we 
know  how  to  fight  them.  In  the  few  years  since  we 
have  known  that  diseases  are  caused  by  germs,  our  sci- 

252 


PREVENTABLE  DISEASES 


253 


entists  have  been  learning  better  each  year  how  to 
destroy  them  and  prevent  them  from  being  scattered 
where  they  will  do  harm.  As  a  result,  the  number  of 
cases  of  illness  and  death  from 
contagious  diseases  has  been 
constantly  diminishing. 

If  these  diseases  are  caused 
by  germs  that  pass  from  the 
sick  to  the  well,  it  will,  of 
course,  be  possible  to  avoid 
them  entirely  if  we  can  only 
find  out  how  the  germs  are 
carried  and  then  devise  some 
means  of  preventing  it.  For 
this  reason  we  call  them  pre- 
ventable diseases.  Already 
we  know  so  much  about  some 
of  the  contagious  diseases  that 
they  could  be  largely,  if  not 
wholly,  prevented  :f  people 
would  only  learn  a  few  simple 
facts  and  follow  a  few  simple 
directions.  The  methods  by 
which  tuberculosis  can  be 
fought  are  given  in  detail 
in  Chapter  XV,  and  most 
of  our  contagious  dis- 
eases could  in  a  similar  way  be  largely  prevented  if 
it  were  only  possible  to  get  people  in  general  to  under- 
stand the  facts.  Without  such  knowledge  people 


FIG.    80.  —  COMPARATIVE 
DIAGRAM. 

The  smaller  figure  represents  the 
number  of  United  States  sol- 
diers killed  by  bullets  as  com- 
pared with  the  larger  figure, 
the  number  killed  by  disease 
in  the  war  with  Spain. 


254 


PHYSIOLOGY  AND  HYGIENE 


will   ignorantly   come   into   contact   with   germs   that 
they  could  easily  avoid.     Nothing  is  more  important 

for  health  than  to  know  the 
causes  of  the  various  preventable 
diseases  and  how  to  avoid  them. 
The  Lesson  taught  by  the 
Japanese. — The  whole  world  was 
given  a  lesson  in  the  prevention 
of  disease  by  the  Japanese  army 
during  the  recent  war  between 
Japan  and  Russia.  In  all  pre- 
vious modern  wars  more  soldiers 
have  died  of  diseases  than  have 
been  killed  by  bullets.  But  the 
Japanese  had  learned  what  the 
scientist  had  to  teach  about  the 
methods  of  preventing  the  par- 
ticular diseases  likely  to  appear 
in  the  army.  They  therefore 
sent  their  doctors  and  scientists 
ahead  of  the  army,  to  find  out 
the  healthy  and  unhealthy  places 
for  camps,  to  learn  whether  the 
water  of  the  streams  and  wells 
was  fit  to  drink,  and  to  discover 
any  other  things  that  might 
make  the  soldiers  sick  when 
they  came  to  camp.  The 
soldiers  were  told  how  important  it  was  for  them  to 
obey  the  directions  of  these  advance  guards,  since  it  was 


FIG.  81.  — COMPARATIVE 

DIAGRAM. 

The  larger  figure  represents 
the  number  of  Japanese 
soldiers  killed  by  bullets, 
as  compared  with  the 
smaller  figure,  the  number 
killed  by  disease  in  the 
war  with  Russia. 


PREVENTABLE   DISEASES  255 

just  as  much  a  matter  of  patriotism  for  them  to  keep 
well  as  it  was  to  be  brave  in  battle.  The  Japanese 
soldiers  obeyed  as  110  other  body  of  men  ever  obeyed 
such  directions,  and  this  gave  the  world  a  chance  to 
see  what  could  be  done  if  men  generally  would  follow 
the  advice  given  by  the  physician  and  the  scientist. 
The  result  was  most  remarkable.  In  our  own  armies 
only  four  years  before,  during  the  war  with  Spain,  for 
every  one  person  killed  by  bullets  four  died  of  disease. 
In  the  Japanese  army  only  one  died  of  disease  for  every 
four  that  were  killed  by  the  enemy.  Preventable  dis- 
eases almost  disappeared.  What  the  Japanese  army 
did  other  people  can  do,  just  as  soon  as  they  will  listen 
to  the  scientific  explanations  of  the  distribution  of  dis- 
ease, and  are  willing  to  follow  directions. 

THE   SOURCE  OF  DISEASE  GERMS 

Although  all  contagious  diseases  are  probably  pro- 
duced by  germs,  each  disease  is  caused  by  a  distinct 
type.  Tiny  as  these  germs  are,  they  are  of  many 
kinds  and  many  different  habits,  so  that  each  one 
needs  to  be  fought  in  its  own  way.  Methods  that  are 
useful  in  preventing  one  disease  are  often  of  no  use 
in  preventing  another.  For  this  reason  each  disease 
must  be  studied  by  itself. 

In  regard  to  the  sources  of  disease  germs,  however, 
one  general  statement  can  be  given.  Disease  germs  come 
from  the  body  of  some  person  or  some  animal  that  has 
the  disease.  The  disease  germs  do  not,  as  a  rule,  live 
long  anywhere  outside  the  living  bodies  of  men  or 


256  PHYSIOLOGY   AND  HYGIENE 

animals.  In  some  cases,  however,  they  are  able  to 
remain  alive  for  a  short  time  after  they  leave  the  body, 
some  kinds  only  a  few  hours,  and  others,  several  months. 
After  they  are  dead  they  are  no  longer  dangerous,  but 
as  long  as  they  are  alive  we  need  to  guard  against 
them.  Hence,  although  their  real  source  is  the  sick 
person  or  animal,  the  germs  may  be  scattered  from  him 
and  reach  a  well  person  from  some  other  source.  With 
diseases  like  tuberculosis,  where  the  germs  can  live  for 
months  outside  the  body,  we  have  to  guard  against 
other  sources  of  the  germs  besides  the  patient. 

It  has  been  generally  believed  that  disease  germs  fre- 
quently cling  to  clothing  and  are  thus  carried  from  a 
sick  to  a  well  person.  While  this  is  occasionally  the 
case,  the  danger  from  this  source  is  really  slight,  less 
than  has  been  supposed.  The  secretions  from  the 
patient,  faeces  or  sputum  or  discharges  from  the  skin,  are 
the  great  sources  of  danger,  and  if  these  are  properly 
disposed  of  there  is  not  much  chance  for  the  germs  to 
adhere  to  clothing.  It  is  extremely  unusual  for  a  person 
visiting  a  sick  room  to  carry  the  germs  in  his  clothing 
to  another  outside. 

In  trying  to  learn  how  to  avoid  the  disease  germs  we 
need  therefore  in  each  case  to  ask  four  questions : 

1.  How    do    the    germs    leave    the    body    of    the 
patient  ? 

2.  How  long  can  they  live  outside  ? 

3.  How  are  they  carried  to  the  well  person? 

4.  How    do    they  get    into    the    body  of  the  well 
person? 


PREVENTABLE   DISEASES  257 

DISEASES  OF  THE  MOUTH  AND  RESPIRATORY 
ORGANS 

Diphtheria.  —  Diphtheria  has  been  one  of  the  most 
dangerous  diseases,  especially  for  children ;  but  fortu- 
nately scientists  have  learned  so  well  how  to  prevent 
and  to  cure  it  that  it  is  much  less  dangerous  than  it 
used  to  be.  It  usually  begins  with  a  sore  throat  and 
with  whitish  spots  on  the  tonsils.  The  white  spots 
spread,  forming  a  membrane  which  grows  down  into 
the  throat,  and  which  contains  great  numbers  of  the 
diphtheria  germs  (Fig.  79,  page  240). 

The  way  in  which  the  germs  injure  the  patient  is 
this.  Growing  in  the  throat  they  secrete  deadly  poisons 
which  are  absorbed  through  the  walls  of  the  throat  into 
the  person's  blood,  and  poison  him.  The  body  has,  how- 
ever, a  very  remarkable  power  of  producing  a  substance 
that  neutralizes  the  effect  of  the  poison.  The  poison  is 
called  a  toxin,  the  neutralizing  substance  is  an  antitoxin. 
The  germs  make  toxins,  the  body  makes  antitoxins.  If 
the  germs  make  toxins  faster  than  the  body  makes  anti- 
toxins the  patient  finally  dies  ;  but  if  the  body  can 
make  antitoxins  fast  enough  to  neutralize  the  toxins, 
he  recovers.  A  few  years  ago  scientists  discovered  a 
way  to  make  animals  produce  this  antitoxin  for  us. 
When  a  person  has  diphtheria  the  doctor  gives  him 
some  of  this  antitoxin  with  the  result  that  the  toxins 
produced  by  the  germs  are  neutralized  quickly  and  the 
person  almost  invariably  recovers  if  it  is  given  early 
in  the  disease.  For  this  reason  the  disease  has  become 
much  less  fatal  than  it  used  to  be. 


258  PHYSIOLOGY  AND  HYGIENE   , 

Diphtheria  is  contagious  because  the  bacteria  adhere 
so  loosely  to  the  walls  of  the  throat  that  they  are  easily 
detached.  Then  they  get  into  the  saliva,  and  will  be 
sure  to  be  left  upon  anything  that  the  patient  may 
have  in  his  mouth:  for  example,  his  fingers,  pencils, 
gum,  drinking  cup,  knife,  fork,  spoon,  etc.  Another 
person  using  the  same  pencil  or  drinking  cup  may  get 
the  germs  in  his  mouth,  arid  may  thus  "  catch "  the 
disease.  Even  after  a  person  has  recovered  from  diph- 
theria, he  usually  carries  the  germs  in  his  mouth  for 
about  three  weeks,  and  during  this  time  he  may  be  the 
means  of  giving  them  to  others. 

We  can  easily  see  how  these  germs  may  be  carried 
from  person  to  person  in  a  family  where  there  are 
several  children,  or  in  a  school,  especially  when  we 
know  that  they  can  remain  alive  for  several  days  after 
leaving  the  mouth.  Any  object  that  has  been  in  the 
mouth  of  a  person  who  has  recently  had  the  disease 
may  give  the  disease  to  another  who  puts  it  into  his 
mouth.  The  best  safeguard  is,  therefore,  never  to  put 
into  the  mouth  anything  that  another  has  had  in  his 
mouth,  and  to  keep  away  as  much  as  possible  from  per- 
sons who  have  sore  throats.  The  health  officer  will  see 
that  sick  persons  are  kept  from  school  as  long  as  they  are 
capable  of  shedding  the  germs.  Sometimes  a  person  who 
is  perfectly  well  may  have  the  germs  in  his  throat,  and 
the  germs,  although  not  injuring  him,  would  be  danger- 
ous to  another  person.  Hence  it  occasionally  becomes 
necessary  to  keep  out  of  school  a  pupil  who  is  perfectly 
well,  but  who  has  the  diphtheria  germs  in  his  throat. 


PREVENTABLE   DISEASES  259 

Tonsilitis. — Tonsilitis  is  also  accompanied  by  a  sore 
throat  and  fever,  but  it  is  much  less  serious  than  diph- 
theria, usually  lasting  only  a  few  days.  The  only 
means  known  for  avoiding  it  is  to  keep  away  from 
those  who  are  ill.  The  germ  that  causes  it  is  not 
known,  and  we  do  not  know  how  it  is  carried. 

Mumps.  —  Mumps  is  chiefly  a  disease  of  children, 
although  grown  people  have  it  occasionally.  The 
glands  of  the  cheeks  and  jaws  become  swollen  and  pain- 
ful, and  it  is  difficult  to  move  the  mouth  to  chew  or 
swallow.  To  avoid  it  one  must  keep  away  from  those 
who  have  the  disease,  and  patients  should  be  kept  out 
of  school  until  well.  No  one  has  yet  discovered  the 
germ  that  causes  mumps  or  how  it  is  distributed. 

Influenza  or  La  Grippe.  —  The  grip  closely  resembles 
a  cold  and  is  sometimes  difficult  to  distinguish  from 
one.  It  is  certainly  contagious,  and  the  germ  that 
causes  it  is  sure  to  be  in  the  mouth  and  nose,  and  in 
the  sputum  and  discharges  from  the  nose  of  the  patient. 
These  discharges  should  therefore  be  treated  like  the 
sputum  of  consumptives,  received  in  cloths  to  be  burned, 
boiled,  or  otherwise  destroyed.  Where  possible  the 
patient  should  be  isolated  from  others,  especially  from 
old  people,  who  are  most  likely  to  take  the  disease  and 
with  whom  it  is  most  serious.  The  grip  is  more  serious 
than  a  cold  and  sometimes  its  effects  last  for  weeks. 
It  occasionally  leads  to  pneumonia  by  decreasing  the 
person's  resistance  to  the  pneumonia  germ.  We  know 
of  no  means  to  prevent  it  except  by  avoiding  patients 
as  much  as  possible  and  by  keeping  up  the  general 


260  PHYSIOLOGY  AND  HYGIENE 

health  by  good  food,  exercise,  and  especially  by  plenty 
of  outdoor  air. 

Pneumonia.  —  Pneumonia  is  a  very  serious  disease  of 
the  lungs  caused  by  a  germ  and  not,  as  is  sometimes 
supposed,  by  a  cold.  The  germ  is  frequently  found  in 
the  mouths  of  well  persons,  doing  them  no  injury ;  but, 
if  the  lungs  become  inflamed  by  a  "  cold  on  the  lungs," 
the  pneumonia  germs  may  find  a  chance  to  enter  at 
the  inflamed  places,  thus  causing  the  disease.  For 
this  reason  a  cold  in  the  chest  should  be  given  par- 
ticular attention. 

Pneumonia  is  sometimes  contagious,  and  several  cases 
sometimes  follow  each  other  in  a  family.  The  sputum 
of  the  patient  contains  the  germs  and  should  therefore 
be  carefully  handled  and  burned  or  disinfected.  The 
danger  of  contagion  is,  however,  slight,  but  other  mem- 
bers of  the  family  should  not  be  allowed  to  come  into 
too  close  contact  with  the  patient.  The  need  of  fresh 
air  is  greater  in  pneumonia  than  in  any  other  disease, 
and  sometimes  people  are  enabled  to  recover  from  this 
disease  by  giving  them  pure  oxygen  to  breathe. 

DISEASES  ASSOCIATED  WITH  THE  DIGESTIVE  ORGANS 

Typhoid  Fever.  —  Typhoid  fever  is  one  of  the  more 
serious  preventable  diseases.  It  is  marked  by  a  fever 
which  continues  for  days  and  sometimes  for  weeks.  It 
makes  a  person  very  ill  and  results  in  death  in  about 
one  case  in.  ten.  Even  when  the  person  recovers,  it  is 
likely  to  leave  him  weak  and  unable  to  work  for  months. 
The  cause  of  the  disease  is  a  bacillus  (Fig.  79,  page  240), 


PREVENTABLE  DISEASES 

that  grows  in  the  intestine  in  immense  numbers  and  is 
passed  from  the  body  with  the  faeces.  Sometimes  it  is 
in  the  kidneys  and  passes  off  in  the  urine.  For  another 
person  to  "  catch  "  the  disease,  the  germs  must  get  into 
his  mouth  and  be  swallowed.  Since  the  germs  can  pass 
from  the  patient's  body  only  in  the  ways  described, 
typhoid  fever  does  not  commonly  pass  directly  from 
person  to  person,  although  it  does  sometimes. 

But  the  germs  can  remain  alive  outside  the  body  for 
some  weeks.  Hence  there  are  other  indirect  means  by 
which  they  may  reach  a  well  person,  and  it  is  against 
these  that  we  need  especially  to  be  on  our  guard. 

By  water.  —  If  the  excretions  from  a  patient  are 
thrown  upon  the  ground  they  may  be  washed  into  a 
well  (Fig.  93).  If  they  are  put  into  closets  they  pass 
into  the  sewers  and  hence  into  a  stream  or  the  ocean. 
In  each  case  the  water  will  be  contaminated  with  the 
germs,  which  will  remain  alive  and  ready  to  do  mischief 
for  about  six  weeks.  The  water  from  such  wells  or 
streams  is  unfit  to  drink.  Clearly,  then,  we  should 
carefully  protect  water  from  all  sewage.  If  it  should 
be  necessary  to  use,  for  drinking,  water  that  has  the 
slightest  opportunity  for  being  mixed  with  sewage,  the 
water  should  be  boiled  in  order  to  kill  the  germs  and 
render  them  harmless. 

By  milk.  —  Sometimes  a  milkman  washes  his  milk 
cans  in  water  from  a  well  or  a  stream,  and  if  the  water 
is  contaminated  with  sewage,  the  typhoid  bacilli  may 
thus  get  into  the  can.  The  germs  will  then  grow  in 
the  milk  and  people  drinking  it  may  take  the  disease. 


262 


PHYSIOLOGY   AND   HYGIENE 


Hundreds  of  cases  have  been  known  to  appear  in  a  city 
almost  at  once,  as  the  result  of  a  single  day's  contami- 
nated milk.  The  only  absolute  safety  against  this  is  to 
kill  the  germs  by  pasteurizing  the  milk  (heating  it  to 
about  150°  F.  for  a  few  minutes). 

By  flies.  —  Flies  may  feed  upon  the  faeces  of  typhoid 
patients  if  exposed  to  the  air,  and  while  doing  so  they 

will  be  sure  to  get  the 
germs  upon  their  feet. 
Then,  if  they  fly  into  our 
dining  rooms  and  light 
on  our  food  or  eating 
utensils,  they  may  leave 
the  germs  so  that  we 
swallow  them  when  we 
drink  or  eat.  It  has 
been  urged  that  the 
house  fly  should  be  called 
the  "typhoid  fly,"  to 
keep  ever  before  us  its 
dangerous  power  in  this 
respect.  Keep  flies  out 
of  the  house  and  away  from  all  food  or  eating 
utensils. 

By  oysters  and  shellfish.  —  Oysters  and  clams  grow- 
ing near  the  outlet  of  sewers  may  become  contaminated 
with  the  typhoid  germs.  If  they  are  afterwards  eaten 
raw,  the  living  germs  may  be  taken  into  the  stomach. 
If  the  oysters  are  cooked,  there  is  no  danger. 

Hook  Worm  Disease.  —  Hook  worm   disease,  as  our 


FIG.  82.  —THE  COMMON  HOUSE  FLY. 


PREVENTABLE   DISEASES 


263 


scientists  have  recently  found,  affects  many  people  in 
the  southern  states.  It  is  caused  by  a  tiny  worm  that 
lives  in  great  numbers  in  the  intestine.  The  patient 
does  not  realize  that  he  is  ill,  for  the  disease  simply 
makes  him  weak  and  indolent;  and 
his  friends  perhaps  think  him  lazy, 
when  he  is  really  an  invalid. 

The  disease  is  chiefly  associated  with 
and  chiefly  acquired  from  filthy  hab- 
its. The  eggs  of  the  worms  pass  out 
of  the  body  with  the  faeces  and  de- 
velop into  little  worms  too  small  to  be 
seen  by  the  eye.  These  remain  alive 
on  the  ground  and  are  likely  to  catch 
upon  a  person's  bare  feet.  Here  they 
first  cling  to  the  skin  and  later  bore 
their  way  through  into  the  blood  vessels 
and  finally  into  the  intestine.  Most 
cases  of  the  disease  are  thus  due  to 

filthy  habits  and  bare  feet,  although 

,1  ,1  i  i  -   i      .1        a,  natural  size. 

there  are  other  means  by  which  the 

worms  may  get  into  the  intestine.  The 
disease  may  be  largely  avoided  by  clean- 
liness and  by  wearing  shoes. 

Cholera.  —  Cholera  is  a  germ  disease 
that  has  been  common  in  some  eastern 
countries,  but  hardly  known  in  the  United  States. 
Since  it  was  discovered  that  the  germ  is  distributed  by 
contaminated  drinking  water,  the  disease  has  almost 
entirely  disappeared  from  Europe. 


FIG.  83.  —  THE 
HOOK  WORM. 


an  adult  worm, 
magnified, 
c,  a  young  worm 
ready  to  enter 
the  body  through 
the  skin. 


264 


PHYSIOLOGY  AND  HYGIENE 


the    southern 
states.    Its  most 


DISEASES  OF  THE  BLOOD 

Malaria.  —  Malaria,  chills  and  fever,  fever  and  ague, 
are  all  the  same  disease  and  are  caused  by  tiny  parasites 
that  live  in  the  red  corpuscles  of  the  blood. 

The  disease  is 
found  all  over 
the  country, 
though  it  is  less 
common  and  less 
serious  in  the 
northern  than  in 

FIG.  84. — ANOPHELES. 
The  mosquito  that  distributes  malaria. 

common  symptom  is  the  appearance  of  a  chill  followed 
by  a  fever,  and  then  a  period  in  which  the  person  feels 
better,  though  he  soon  has  another  chill  with  its  fever. 
These  periods  follow  with 
regularity  every  two  days 
as  a  rule,  though  sometimes 
every  day  or  every  three 

yS*  FIG.  85.  —  CULEX. 

The  disease  is  especially  The  common  mosquito.    It  does 

common  around  swamps,  not  carry  malaria.  Note  that  it 
and  it  was  forme  rly  thought  assumes  a  different  posture  from 
to  come  from  breathing  that  of  Anopheles  (FIG.  84). 
the  damp  air,  especially  the  night  air  of  infested  locali- 
ties. We  now  know  that  the  air  itself  is  not  danger- 
ous, but  that  the  disease  is  spread  only  by  the  mos- 
quitoes that  may  be  in  the  air.  Only  one  kind  of 


PREVENTABLE  DISEASES  265 

mosquito  is  to  blame,  and  this  one  not  unless  he  has 
previously  bitten  some  one  who  has  malaria.  If  this 
kind  of  mosquito,  that  is  called  Anopheles,  bites  a  person 
who  has  the  disease,  it  sucks  the  blood  with  the  germs 
into  its  body.  If  the  same  mosquito  later  bites  a  well 
person,  it  may  inoculate  him  with  the  germs  that  have 
grown  from  those  in  the  blood  of  the  first  patient. 

Now  that  we  know  this  fact  we  can  prevent  malaria, 
if  we  can  protect  ourselves  against  mosquito  bites. 
Mosquito  nettings  at  windows  and  doors  are  a  good 
protection  against  the  disease,  and  the  destruction  of 
the  breeding  places  of  the  mosquitoes  is  even  better. 
Mosquitoes  breed  in  pools  of  stagnant  water  and,  if 
these  are  filled  up  or  drained,  the  mosquitoes  disappear. 
A  little  kerosene  put  on  the  surface  of  such  pools  will 
spread  rapidly  and  smother  the  mosquito  young. 
Barrels  and  cisterns  of  rain  water  also  furnish  good 
breeding  places.  As  fast  as  the  mosquitoes  disappear, 
malaria  disappears  also. 

It  is  important  to  remember  that  the  malaria  mosquito 
only  flies  at  night.  This  is  doubtless  the  reason  why 
people  have  believed  so  long  that  night  air  is  unwhole- 
some. But  if  we  only  get  rid  of  mosquitoes,  night  air 
is  not  injurious,  and  if  we  use  mosquito  nettings  we  may 
keep  the  windows  open  all  night  without  fear. 

Yellow  Fever.  —  Yellow  fever  is  another  disease  dis- 
tributed by  mosquitoes,  but  we  do  not  yet  know 
whether  it  is  a  disease  of  the  blood.  The  disease  is  a 
very  serious  one  and  is  generally  fatal.  Fortunately, 
it  is  not  common  in  this  country,  being  found  chiefly  in 


266 


PHYSIOLOGY   AND   HYGIENE 


warm,  tropical  climates.  Occasionally  it  has  invaded 
our  southern  states,  producing  frightful  epidemics  and 
killing  thousands  of  people.  A  few  j^ears  ago  three 

scientists  went 
to  the  warm  cli- 
mates to  study 
the  disease. 
Thinking  that  it 
was  carried  by 
FIG.  86.— STEGOMYIA.  mosquitoes  they 

The  mosquito  that  distributes  yellow  fever,      allowed    t  h  e  m- 

selves  to  be  bitten  by  mosquitoes  that  they  suspected, 
and  one  of  them  took  the  disease  and  died  of  it.  He 
was  a  hero,  just  as  brave  as  one  who  fights  in  battle, 
and  his  death  has  been  one  of  the  great  benefits  to 
mankind,  for  it  has  shown  us 
how  to  stop  this  frightful 
disease. 

To  fight  the  mosquito  is  to 
fight  yellow  fever.  It  is  not 
the  common  mosquito  that  is 
to  blame,  nor  is  it  the  same 
one  that  carries  malaria.  To 
stop  yellow  fever  the  breeding 
places  of  mosquitoes  should  be 
destroyed,  or  covered,  to  pre-  Fl(/87.  _THE  FLEA  (greatly 
vent  mosquitoes  from  getting  magnified), 

into  them  to  lay  their  eggs.  The  patient,  too,  is  to  be 
guarded  from  mosquitoes,  since  it  is  only  by  biting  a 
patient  that  the  insect  obtains  the  germs  and  can  thus 


PREVENTABLE  DISEASES 


267 


carry  the  disease.  For  this  reason,  yellow  fever 
patients  are  now  kept  carefully  covered  by  mosquito 
netting,  so  that  the  insects  cannot  bite  them. 

Since  this  way  of  fighting  yellow  fever  has  been 
followed,  the  disease  has  lost  most  of  its  terror.  In 
Havana,  and  in  Panama,  where  yellow  fever  was  always 
found  before  this  discovery,  it  has  now  almost  dis- 
appeared. One  epidemic  in  New  Orleans,  which  started 
before  the  people  understood  the  danger  of  mosqui- 
toes, was  quick- 
ly stopped  when 
they  began  to 
fight  rn  o  s  q  u  i- 
toes. 

The  mosquito, 
then,  proves 
itself  a  deadly 
enemy,  since  it  FIG.  88.  — THE  RAT. 

is  the  means  of  This  animal  is  largely  responsible  for  the  dis- 
distribu  ting  two  tribution  of  the  bubonic  plague, 

most  serious  diseases.  Money  spent  in  its  extermina- 
tion is  well  invested,  and  every  one  should  be  glad  to 
aid  in  the  work  of  destroying  it. 

Bubonic  Plague.  —  The  plague  is  another  disease  that 
is  distributed  by  the  aid  of  insects.  In  this  case  it  is 
usually  the  flea  that  gives  it  to  man  by  biting  him. 
The  flea  usually  gets  the  infection  from  rats.  To  pre- 
vent the  plague,  therefore,  the  best  plan  is  to  kill  all 
rats.  This  disease  is  very  common  in  India,  but  has 
appeared  in  this  country  in  a  few  instances. 


268  PHYSIOLOGY   AND   HYGIENE 

DISEASES   ACCOMPANIED   BY  A   SKIN   ERUPTION 

Scarlet  Fever,  Measles,  Chicken  Pox.  —  We  notice  scar- 
let fever,  measles,  and  chicken  pox  together,  not  because 
they  are  really  alike,  but  because  they  are  all  accompa- 
nied by  the  appearance  of  blotches  or  colored  spots  on 
the  skin,  and  because  we  have  to  follow  the  same  means 
for  prevention.  Scarlet  fever  and  measles  are  apt  to 
produce  severe,  sometimes  fatal,  illness,  while  chicken 
pox  is  never  serious.  The  germs  that  cause  these  dis- 
eases are  not  yet  known,  but  the  infection  probably 
passes  from  the  skin  of  the  patient. 

It  is  particularly  hard  to  guard  against  a  disease  that 
is  spread  by  skin  eruptions,  and  for  this  reason  these 
diseases  are  very  contagious.  The  only  method  of  avoid- 
ing their  spread  is  by  keeping  the  patient  from  associa- 
tion with  others,  who  are  liable  to  take  the  disease,  until 
the  time  is  passed  when  he  can  convey  the  infection  to 
others.  The  time  that  he  must  be  thus  quarantined 
varies  in  the  different  diseases  from  two  to  six  weeks. 
It  is  sometimes  hard  to  keep  a  child  separated  from  his 
playmates  so  long  after  he  has  quite  recovered  from  his 
illness,  but  this  is  the  only  way  to  prevent  the  spread  of 
the  disease.  Most  towns  and  cities  have  regulations 
planned  to  prevent  these  diseases  from  spreading  from 
scholar  to  scholar  and  becoming  epidemics  in  the  schools. 

Smallpox.  —  Smallpox  is  one  of  the  most  dangerous 
diseases,  and  in  former  times  was  a  frightful  scourge, 
causing  an  immense  number  of  deaths.  To-day  it  is 
much  less  common  than  it  used  to  be,  and  has  come  to 


PREVENTABLE  DISEASES  269 

be  placed  in  the  class  of  preventable  diseases.  The 
method  of  fighting  it  involves  two  factors  :  (1)  isolation 
of  the  patient  from  well  persons,  and  (2)  vaccination. 
In  countries  where  vaccination  is  enforced  by  law  the 
number  of  cases  of  smallpox  is  low.  In  order  that  im- 
munity be  lasting,  however,  a  person  should  be  revac- 
cinated,  since  the  effect  of  a  single  vaccination  lasts  only 
a  few  years.  Doctors  who  have  to  treat  smallpox 
patients  are  themselves  vaccinated  every  few  years,  and 
are  thus  made  immune  so  that  it  is  safe  for  them  to  visit 
patients.  If  every  one  would  take  this  precaution, 
smallpox  would  probably  disappear  entirely. 

MISCELLANEOUS   PREVENTABLE   DISEASES 

Boils,  Abscesses,  Inflammation,  Erysipelas,  Blood 
Poisoning. — Every  one  is  familiar  with  the  sores,  some- 
times small  and  sometimes  large  and  painful,  called 
boils  and  abscesses.  Most  people,  too,  have  learned  by 
experience  that  if  one  cuts  or  bruises  himself  the 
wound  sometimes  becomes  red  and  painful  after  a 
few  days,  and  we  say  it  is  inflamed.  Probably,  too, 
we  have  all  heard  of  cases  of  erysipelas  and  of  blood 
poisoning  which  make  persons  very  ill  and  sometimes 
produce  death. 

Although  these  troubles  seem  very  different,  they 
are  all  produced  by  the  same  kind  of  germs  (Fig.  79). 
These  germs  are  about  us  at  all  times,  on  our  clothes, 
on  our  hands  and  faces,  in  our  mouths,  etc.,  but  com- 
monly they  do  no  harm.  They  cannot  trouble  us  as 
long  as  they  are  simply  in  the  mouth  or  on  the  skin, 


270  PHYSIOLOGY  AND   HYGIENE 

and  to  do  us  any  injury  they  must  get  through  the 
skin  into  the  blood  or  lymph  within.  If  the  skin  is 
broken,  bruised,  or  even  scratched,  they  may  get  in  and 
grow,  causing  inflammation,  a  boil,  or  some  form  of 
blood  poisoning.  If  we  can  keep  them  out,  we  shall 
prevent  this  kind  of  troubles.  All  wounds,  cuts  or 
bruises,  and  scratches  also,  should  therefore  be  care- 
fully cleaned.  Use  for  this  purpose  only  perfectly 
clean  water.  Better  still,  wash  the  wound  with  an 
antiseptic  solution,  like  a  weak  solution  of  carbolic 
acid  (one  part  to  twenty),  which  will  destroy  the  germs. 
If  one  will  only  keep  on  hand  such  a  carbolic  solution 
or  some  antiseptic  ointment,  and  get  into  the  habit  of 
washing  all  cuts  and  scratches  with  it  he  will  prevent 
many  a  troublesome  sore,  and  ward  off  possibly  some 
severe  cases  of  blood  poisoning. 

The  condition  of  one's  general  health  is  one  of  the 
most  important  factors  in  warding  off  trouble  from 
skin  wounds.  For  if  the  body  is  in  a  good  healthy 
condition,  it  has  considerable  power  of  resisting  these 
particular  germs,  so  that  even  after  they  get  in  through 
the  skin  they  do  not  succeed  in  growing.  If  a  person 
by  improper  life  allows  his  general  health  to  be  injured, 
this  power  of  resistance  becomes  so  slight  that  every 
scratch  he  has  becomes  inflamed,  and  he  may  have  one 
boil  after  another.  We  then  say  that  the  blood  is  "in 
bad  condition."  The  fact  is  that  the  body  in  general 
has  lost  much  of  its  power  of  resisting  the  attack  of  germs 
that  may  get  in  through  the  skin.  To  avoid  this,  one 
needs  simply  to  follow  the  general  laws  of  good  health: 


PREVENTABLE  DISEASES  271 

by  eating  good,  wholesome,  and  not  too  rich  food, 
taking  plenty  of  exercise  in  the  open  air,  getting  proper 
sleep,  and  abstaining  from  alcohol  and  tobacco. 

There  are  certain  kinds  of  wounds  that  need  particu- 
lar care  : 

Punctured  wounds  are  produced  by  sharp  instruments 
that  penetrate  the  flesh,  like  nails,  needles,  bits  of  glass, 
splinters,  etc.  These  wounds  do  not  bleed  much  and 
appear  less  serious  than  a  surface  wound  that  bleeds 
profusely.  But  this  makes  them  more  likely  to  be 
troublesome.  The  object  that  produces  such  a  wound 
should  be  removed,  and  this  is  sometimes  difficult  when 
a  piece  of  glass  or  a  long  splinter  is  imbedded  in  the 
flesh.  But  as  long  as  the  object  remains  there  is  likely 
to  be  trouble.  The  wound  should  be  made  to  bleed 
freely  so  that  the  stream  of  blood  shall  wash  away  any 
dangerous  germs  that  may  be  thrust  into  the  flesh. 
Then  the  wound  should  be  carefully  cleaned  with  car- 
bolic acid  solution,  if  possible,  some  of  it  being  squirted 
into  the  wound.  If  the  wound  is  a  deep  one  it  should 
have  the  care  of  a  physician. 

Tetanus,  or  Lockjaw.  —  A  wound  made  by  a  dirty 
object,  like  a  rusty  nail  or  a  sliver  of  wood  lying  on 
the  ground,  is  likely  to  be  more  dangerous  than  any 
other  kind.  This  is  because  in  some  parts  of  the  world 
there  is  in  the  earth  a  deadly  germ  which,  if  it  gets  into 
the  flesh,  may  produce  lockjaw,  or  tetanus.  The  rea- 
son why  wounds  from  toy  pistols,  which  are  so  common 
on  Fourth  of  July,  are  particularly  dangerous  is  because 
the  boy's  hands  are  apt  to  be  dirty  at  the  time,  and  any 


272  PHYSIOLOGY  AND   HYGIENE 

dirty  object  may  have  some  of  these  germs  clinging  to  it. 
Lockjaw  that  comes  from  these  wounds  is  a  very  pain- 
ful disease  and  always  fatal,  so  that  the  only  way  to 
fight  it  is  to  prevent  it.  This  is  one  of  the  chief  reasons 
why  exceptional  care  should  be  taken  to  clean  a  punc- 
tured wound. 

Wounds  made  ~by  fishhooks  are  troublesome,  since  it  is 
sometimes  difficult  to  remove  the  hook  because  of  its 
barb.  They  are  usually  quite  shallow,  and  frequently 
the  easiest  thing  to  do  is  to  push  the  point  through 
the  skin  and  then  cut  off  the  point  with  the  barb  by 
means  of  a  wire  cutter,  when  the  hook  can  easily  be 
removed. 

Particular  caution  is  necessary  against  playing  with 
sharp  objects  like  knives,  scissors,  button  hooks,  etc., 
and  particularly  against  running  with  them  in  the 
hands  or  in  the  mouth.  Many  a  serious  accident  re- 
sulting in  the  loss  of  a  limb  or  of  the  eyes  has  resulted 
from  such  habits. 

Cuts  and  bruises  on  the  feet  should  be  handled  more 
carefully  than  wounds  elsewhere.  This  is  because  one's 
stockings  are  apt  to  be  moist  with  perspiration  and  warm 
from  the  body  heat  so  that  germs  find  in  them  a  very  good 
place  to  grow.  The  stocking  gets  filled  with  troublesome 
germs,  which  inside  the  shoe  come  in  constant  contact 
with  the  wound,  getting  every  opportunity  to  inocu- 
late the  flesh  through  any  break  in  the  skin.  For  this 
reason  serious  sores  are  apt  to  start  with  a  corn,  or  a 
little  broken  skin  around  the  toe  nail,  and  all  cuts, 
bruises,  and  scratches  on  the  feet  should  be  carefully 


PREVENTABLE   DISEASES  273 

cleaned,  washed  with  an  antiseptic  solution,  and  then 
covered  with  clean  cloth  before  the  stocking  is  replaced. 
This  habit  will  prevent  many  a  sore  toe  and,  perhaps, 
some  serious  case  of  blood  poisoning  that  might  result 
in  the  loss  of  a  foot. 

Bites  of  animals  are  more  dangerous  than  ordinary 
wounds  because  in  an  animal's  mouth  there  are  very 
likely  to  be  dangerous  germs,  which  will  be  pretty 
sure  to  be  inoculated  into  the  wounds  made  by  his 
teeth.  Inflamed  wounds  and  blood  poisoning  are  there- 
fore more  apt  to  follow  than  with  ordinary  wounds.  An 
antiseptic  wash  should  never  be  omitted  in  such  cases. 
The  bites  of  dogs  are  sometimes  especially  dangerous, 
since  they  may  produce  hydrophobia. 

Rabies,  or  Hydrophobia.  —  Rabies  is  one  of  the  most 
painful  of  diseases,  but  fortunately  it  is  not  only  rare 
but  preventable.  When  it  occurs,  it  is  always  fatal. 
It  is  commonly  acquired  from  the  bite  of  dogs  that  are 
mad,  or  rabid.  It  should  be  remembered,  however, 
that  the  disease  is  very  rare  among  dogs  and  that  a 
large  proportion  of  dogs  who  bite  are  not  mad  at  all, 
and  their  bites  are  no  more  dangerous  than  the  bites 
of  other  animals.  Many  times  a  dog  will  bite  boys 
who  are  tormenting  him  and  will  then  be  called  mad. 
It  is  not  difficult  for  a  skilled  physician  to  determine 
whether  a  dog  is  really  rabid.  If  the  dog  is  actually 
rabid,  he  will  die  in  a  day  or  two,  and,  after  his  death, 
an  examination  of  his  brain  will  tell  at  once  whether 
or  not  he  was  rabid.  It  is,  therefore,  best  not  to  kill 
at  once  the  dog  who  has  bitten  people,  but  to  keep  him 


274  PHYSIOLOGY   AND   HYGIENE 

confined  to  see  if  he  dies ;  for  if  Tie  does  not  die  it  is  not 
a  real  case  of  rabies. 

If  one  is  bitten  by  a  dog  that  is  really  rabid  or  is 
strongly  suspected  of  being  so,  the  person  bitten  should 
be  taken  at  once  to  a  Pasteur  Institute,  where  he  can 
have  a  treatment  that  will,  in  almost  all  cases,  prevent 
the  development  of  the  disease.  It  is  necessary  to  pro- 
ceed quickly,  however,  since  if  the  disease  once  gets 
started  there  is  no  cure  for  it. 

Rabies  could  soon  be  stamped  out  entirely  if  people 
would  only  consent  to  muzzling  all  dogs  that  roam 
about  the  streets.  In  countries  where  the  law  requires 
this  precaution  the  disease  is  practically  unknown. 

Whooping  Cough.  —  Whooping  cough  is  a  germ  dis- 
ease whose  chief  symptom  is  a  violent  cough  which 
usually  lasts  several  weeks.  A  bacterium  has  been  dis- 
covered which  probably  causes  the  disease,  but  we  do 
not  surely  know  how  it  is  carried  from  person  to  per- 
son. It  is  certainly  contagious,  and  the  contagion  is 
greatest  at  the  time  when  the  patient  is  coughing. 
The  germs  are  in  the  sputum  and  are  passed  from  the 
mouth  or  nose  with  the  breath  during  a  coughing  fit. 
The  only  protection  is  to  avoid  being  close  to  patients 
while  they  are  coughing.  Life  in  the  open  air  is  the 
best  thing  both  for  the  patient  and  for  others  who  wish 
to  avoid  the  disease.  As  long  as  the  cough  continues, 
the  disease  remains  contagious. 

Pink  Eye  and  Trachoma.  —  Pink  eye  is  an  inflamma- 
tion of  the  thin  membrane  that  covers  the  eyeballs  and 
lines  the  lids.  While  temporarily  painful  and  weaken- 


PREVENTABLE   DISEASES  275 

ing    to    the  eyes,  it    does   not  last   more   than  a   few 
days. 

Trachoma,  or  granulations,  is  a  more  serious  disease 
of  the  eyes  and  may  sometimes  produce  blindness.  It 
is  a  roughness  on  the  eyeball  or  eyelids  that  makes  one 
feel  constantly  as  if  dirt  particles  were  in  the  eye.  Both 
of  these  diseases  are  contagious  and  probably  caused  by 
germs.  Towels,  napkins,  or  handkerchiefs  that  have 
been  used  to  wipe  the  eyes  or  face  of  a  person  having 
one  of  these  diseases  are  sure  to  become  infected  with 
the  germs  and  may  cause  the  disease  in  another  using 
them.  For  the  protection  of  the  eyes,  as  well  as  for  the 
purpose  of  preventing  the  spread  of  some  other  diseases, 
the  use  of  a  common  towel  in  schools,  factories,  and  other 
public  places  should  be  abandoned. 

IMMUNITY  AGAINST  GERM  DISEASES 

In  the  case  of  most  germ  diseases,  if  a  person  has 
the  disease  and  recovers,  he  is  for  a  time  protected  from 
a  second  attack.  We  say  he  is  immune.  The  length  of 
this  immunity  is  not  alike  for  all  diseases.  It  lasts  for 
years,  or  sometimes  for  a  lifetime,  in  the  case  of  small- 
pox, scarlet  fever,  chicken  pox,  yellow  fever,  whooping- 
cough,  measles,  and  mumps.  It  lasts  a  much  shorter 
time  in  the  case  of  typhoid  fever,  malaria,  diphtheria, 
grip,  and  tonsilitis,  so  short  in  some  cases  that  there 
hardly  seems  to  be  any  immunity  at  all.  It  will  be 
seen  therefore  that  if  one  has  a  disease  in  the  first  list 
above,  he  is  very  unlikely  ever  to  take  it  again,  and  does 
not  need  for  himself  to  take  special  precautions  against 


276  PHYSIOLOGY  AND   HYGIENE 

contagion.  Such  persons  are  best  for  nurses,  since  they 
are  not  likely  to  take  the  disease  from  the  patient.  But 
a  person  who  has  had  one  of  the  diseases  in  the  second 
list  may,  after  a  few  weeks  or  months,  take  it  again. 

QUESTIONS 

1.  What  is  a  contagious  disease  ? 

2.  What  is  the  chief  source  of  disease  germs? 

3.  What  are  the  methods  by  which  diphtheria  is  carried  from 
person  to  person? 

4.  How  is  the  grip  distributed  ? 

5.  How  is  pneumonia  distributed? 

6.  Give  all  the  methods  by  which  typhoid  fever  is  distributed. 

7.  What  diseases  are  distributed  by  mosquitoes,  and  how  may 
this  be  prevented  ? 

8.  How  may  we  guard   against   diseases  which  have  a  skin 
eruption  ? 

9.  What  precautions    should  we   adopt   to   prevent   inflamed 
wounds  and  blood  poisoning  ? 

10.  Why  are  the  bites  of  animals  more  dangerous  than  ordinary 
wounds? 

11.  What  is  the  cause  of  lockjaw? 

12.  Why  should  the  use  of  common  towels  not  be  allowed  in 
public  places? 

13.  What  is  immunity  ? 


CHAPTER   XV 
A  WAR   FOR  THE   NATION 

EVEEY  boy  and  girl  who  has  studied  American  history 
knows  how  important  it  is,  when  a  battle  is  to  be  fought, 
for  each  army  to  find  out  as  nearly  as  possible  how  many 
men  the  other  side  has,  how  many  cannon,  and  all  that 
can  be  learned  about  the  strength  or  weakness  of  the 
enemy.  The  side  that  does  not  take  these  precautions 
risks  defeat  in  the  struggle. 

So  in  the  great  war  for  the  health  of  the  nation, 
which  is  now  being  waged,  we  must  first  of  all  study 
the  nature  and  resources  of  our  enemy. 

TUBERCULOSIS 

It  is  not,  as  a  rule,  a  good  thing  to  think  very  much 
about  diseases.  We  should  think  rather  of  how  to 
make  our  bodies  strong  and  keep  them  so ;  and  then,  in 
case  the  germs  of  disease  attack  us,  we  shall  have  the 
very  best  means  of  defense. 

What  We  Have  to  Face. — There  is,  however,  one 
disease,  the  most  widespread  and  deadly  of  any  known 
to  man,  which,  if  we  all  knew  its  causes  and  how  to 
guard  against  it,  might  perhaps  be  entirely  stamped 
out.  We  surely  should  be  eager  to  learn  everything 
that  we  can  about  it,  so  as  to  save  ourselves  and  others 
from  its  attacks. 

277 


278  PHYSIOLOGY  AND   HYGIENE 

This  terrible  disease  is  tuber- 
culosis, which  we  generally  hear 
spoken  of  as  consumption. 

When  we  study  about  our  Civil 
War  we  are  shocked  at  the  terrible 
loss  of  life  in  battle,  yet  the  number 
killed  in  battle  during  that  entire 
war  was  not  as  great  as  the 
number  of  those  who  die 
from    tuberculosis    in    the 
United   States  every  year. 
Is  it  not  true,   then,  that 
our  nation  is  in  great 
danger  and  that  we 
should     study    how 
best  to  defend  it  ? 

The  Hopeful  Side. 
— This  would  be  a 
terrifying  picture  in- 
deed if  there  were 
not  a  hopeful  side, 
which  depends,  how-  FIG.  89.  — DIAGRAM  ILLUSTRATING  THE 

ever,  upon  every  man    DEATHS  DuE  T0  Fou*  YEARS  OF  CIVIL 
WAR  AND  DEATHS  CAUSED  BY  TUBERCU- 

and  woman  and  boy    L0sis  FOR  1900-04  RELATIVELY  COMPARED. 
and  girl  throughout 

the  country  knowing  the  danger  and  doing  his  share 
to  overcome  it. 

CONSUMPTION  NOT  HEREDITARY 
The  Tubercle  Bacillus — Until  very  recently  tuber- 
culosis, or  consumption,  was  considered  a  hereditary 


A  WAR  FOR  THE   NATION  279 

disease,  which  could  neither  be  prevented  nor  cured, 
and  against  which  it  was  therefore  useless  to  fight. 
The  causes  were  unknown,  and  no  medicine  could  be 
relied  upon  to  effect  a  cure. 

But  not  many  years  ago  it  was  discovered  that 
tuberculosis  is  caused  by  a  small  plant  called  tubercle 
bacillus,  so  small  indeed  that  it  can  be  seen  only  with 
a  microscope.  Since  this  plant  may  be  breathed  in 
with  the  dust  in  the  air,  it  is  most  often  found  in  the 
lungs,  though  it  may  attack  other  parts  of  the  body. 

The  discovery  of  this  tiny  bacillus  proved  first  of  all 
that  the  disease  cannot  be  inherited,  because  it  would 
be  impossible  for  a  plant  organism  of  this  kind  to  be 
passed  on  from  parents  to  children.  A  child  might 
appear  to  inherit  the  disease  when,  as  a  matter  of  fact, 
the  disease  was  " caught"  while  the  child  was  very 
young  from  its  mother  or  some  one  else  in  the  family 
who  was  ill  with  it. 

CONSUMPTION  CAN  BE  PREVENTED 

Disease  Spread  by  Contact — Then,  the  discovery  and 
study  of  this  bacillus  also  showed  that  the  disease  can 
be  prevented.  No  one  can  have  consumption  unless 
he  in  some  way,  directly  or  indirectly,  comes  in  con- 
tact with  a  person  who  is  a  consumptive;  and  even 
then,  if  proper  care  be  taken  to  prevent  contagion,  or 
if  his  body  is  in  good  condition,  he  is  in  no  danger. 
But  people  do  not,  as  a  rule,  know  how  to  take  the 
proper  care,  and  that  is  the  reason  why  the  disease  is 
so  widespread  and  so  dangerous. 


280  PHYSIOLOGY  AND   HYGIENE 

How  the  Bacillus  Travels. — The  common  means  by 
which  the  bacillus  leaves  the  body  of  the  sick  per- 
son, if  the  disease  is  in  the  lungs,  is  by  means  of  the 
"  spit,"  or  sputum,  as  it  is  more  properly  called,  which 
is  the  matter  coughed  up  from  the  diseased  lungs.  If 
this  is  allowed  to  soil  the  hands  or  clothes  of  the 
patient,  or  articles  used  by  him,  or  if  allowed  to  dry 
upon  the  floor  so  as  to  become  powdered  and  mingle 
with  the  dust,  anyone  who  comes  into  the  room  may 
get  the  bacteria  on  his  hands  and  so  into  his  mouth,  or 
may  breathe  them  into  his  lungs.  Then,  if  the  condi- 
tions are  favorable,  the  disease  develops. 

For  those  who  come  in  contact  with  a  consumptive 
in  this  manner,  we  shall  explain  in  the  section  on 
"  Precautions  for  Consumptives  "  how  all  danger  from 
direct  contact  with  a  patient  may  be  avoided. 

The  Crime  of  Spitting. — But  it  is  by  indirect  contact 
that  the  disease  has  been  spread  so  widely,  and  this 
is  brought  about  by  the  filthy  and  unnecessary  habit 
of  spitting  upon  the  floors  or  walls  of  a  room,  upon 
sidewalks,  or  in  cars  and  other  public  places.  Each 
bit  of  phlegm,  or  sputum,  deposited  in  this  way,  may 
contain  thousands  of  bacteria,  and  when  the  sputum 
becomes  dry  it  flies  about  in  the  air  as  dust,  and  is 
breathed  in  by  everyone  in  the  vicinity.  It  would 
not  be  strange  if  among  a  number  of  people  present 
anywhere  there  should  be  some  whose  bodies  were  in 
a  more  or  less  weakened  condition  from  one  cause  or 
another;  and  so  the  disease  is  continually  finding  new 
victims. 


A  WAR  FOR  THE  NATION  281 

It  is  safe  to  say  that  if  all  spitting  about  rooms  or  in 
public  places,  or  anywhere  but  in  vessels  provided  for 
the  purpose,  could  be  done  away  with,  we  should  have 
gone  a  long  way  toward  stamping  out  the  disease  of 
tuberculosis. 

And  when  we  consider  that  this  simple  precaution, 
with  proper  care  of  the  people  who  actually  have  the 
disease,  would  result  in  the  saving  of  thousands  of  lives 
in  our  own  country  every  year,  it  is  clearly  worth  our 
while  to  do  all  that  we  can  to  help  bring  this  about. 

SOME  WONDERFUL  RESULTS   OF  THE   STRUGGLE 

The  actual  results  of  the  war  against  this  disease  in 
places  where  the  people  have  been  taught  the  facts 
about  it  that  are  given  in  this  chapter,  and  have  worked 
together  to  stamp  it  out,  have  been  marvelous. 

In  Maine,  where  pamphlets  giving  such  facts  and 
simple  rules  and  precautions  were  distributed  through- 
out the  State,  the  number  of  deaths  from  consumption 
decreased  from  1,352  in  1892  to  901  in  1903— a  decrease 
of  from  20.24  per  cent,  of  deaths  per  10,000  inhabitants 
to  12.97  per  cent,  for  the  same  number. 

In  the  two  largest  boroughs  of  New  York  City,  where 
the  most  vigorous  fight  is  being  carried  on,  the  death 
rate  from  pulmonary  tuberculosis  has  decreased  from 
4.27  per  cent,  in  1881  to  2.29  per  cent,  in  1903,  though 
during  the  same  time  the  population  has  greatly  in- 
creased.1 

1  These  figures  are  given  for  1903  because  some  special  circum- 
stances affected  the  comparative  death  rate  of  the  later  years,  which 
would  require  too  much  adjustment  and  explanation. 


282  PHYSIOLOGY   AND  HYGIENE 

CONSUMPTION   CAN   BE   CURED 

The  third  important  result  of  the  discovery  of  the 
tubercle  bacillus  and  its  nature  is  the  knowledge  that 
consumption  is  not  at  all  a  hopelessly  fatal  disease,  but 
can  be  cured  if  taken  in  time  and  treated  in  the  proper 
way.  Everyone  ought  to  know  about  this,  so  that 
even  if  he  does  not  need  the  information  for  himself, 
he  may  be  able  to  tell  others  who  do  need  it. 

Dangers  from  the  Bacteria. — For  the  protection  ol 
others,  as  well  as  of  the  patient  himself,  the  sputum 
should  be  destroyed  immediately  by  being  coughed 
into  paper  napkins  which  can  be  burned,  or  into  cups 
containing  a  weak  solution  of  carbolic  acid  or  some 
other  sterilizing  material;  these  cups  should  be  washed 
frequently  with  hot  water  and  strong  soap  or  lye.  It 
is  better  not  to  use  handkerchiefs  or  cloths;  put  into 
the  pocket,  they  will  soil  the  clothes.  The  hands  and 
mouth  should  be  washed  very  frequently  in  warm  water 
and  soap.  As  the  saliva  or  the  small  drops  of  moisture 
coughed  or  sneezed  out  may  contain  the  bacteria,  equal 
care  should  be  taken  to  cover  the  mouth  and  nose  with 
a  paper  napkin,  and  thus  prevent  the  distribution  of 
the  bacteria  in  this  way. 

The  patient  may,  by  taking  these  precautions,  effect- 
ually guard  against  spreading  the  disease  among  those 
with  whom  he  daily  comes  in  contact.  In  fighting 
the  tubercle  bacillus,  the  patient  should  take  every 
precaution  to  prevent  the  possibility  of  new  growths 
developing  in  his  own  system,  as  well  as  to  use  such 
preventive  measures  as  he  can,  to  avoid  distributing 
the  disease  among  others. 


A   WAR  FOR  THE  NATION 


283 


Special  directions  with  regard  to  articles  that  are 
convenient  for  use  will  be  given  under  "  Precautions 
for  Consumptives." 

Importance  of  Fresh  Air.  —  First,  the  patient  must 
have  all  the  fresh  air  possible,  night  and  day,  summer 
and  winter.  The  air  should  be  in  circulation,  and  with 
warm  clothing  and  something  wrapped  about  the  head, 
no  one  need  be  afraid  of  "  draughts."  There  must  be 
draughts,  that  is, 
currents  of  air,  in 
order  to  keep  the 
air  absolutely 
pure  and  to  ensure 
the  large  supply  of 
oxygen  needed. 

If  possible,  the 
patient  should  live 
and  sleep,  summer 
and  winter,  in  a 
well  ventilated 
tent  or  on  a  ver- 
anda. It  is  now 
claimed  by  many 
physicians  that 

climate  has  little  FIG.  90.—  A  SLEEPING  VERANDA  ENCLOSED  BY 
to  do  either  with  AWNING  AT  A  CONSUMPTIVE'S  HOME. 

causing  or  curing  consumption.  Still,  if  the  patient 
does  not  need  to  consider  expense,  there  is  an  advan- 
tage in  his  going  to  some  health  resort.  A  change  of 
climate  is  usually  beneficial,  and  he  is  likely  also  to 


284  PHYSIOLOGY  AND  HYGIENE 

receive  better  care  than  he  could  have  at  home.  How- 
ever, when  cases  of  tuberculosis  are  taken  in  time,  the 
patient  can  generally  be  cured  in  his  own  home,  pro- 
vided that  he  will  live  out  of  doors  and  will  follow 
some  other  special  directions. 

Nourishing  Food. — After  the  fresh  air  comes  food. 
The  science  of  curing  consumption  consists  simply  in 


______ 

FIG.  91.— THE  SUN  PARLOR  OP  A  LARGE  HOSPITAL. 

taking  in  all  the  oxygen  that  can  be  secured,  in  order 
to  purify  the  blood,  thus  enabling  the  tissues  of  the 
body  to  get  all  the  nourishment  possible  out  of  the 
food.  At  the  same  time  it  is  important  to  take  all  the 
nourishing  food  possible.  If  enough  nourishment  can 
be  taken  so  that  the  tissues  will  be  built  up  faster  than 
the  disease  can  break  them  down,  the  cure  of  the  pa- 
tient is  assured. 

Last  of  all,  but  very  important  to  the  cure,  come 
carefully  regulated  exercise  and  rest. 


A   WAR   FOR   THE   NATION  285 


HOW  TO   COMBAT   BACTERIA 

Healthy  Tissues  Resist  Disease. — The  measures  we 
must  employ  for  keeping  the  bacteria  out  of  our  own 
systems,  or  throwing  them  off  if  they  do  enter,  are 
very  simple. 

The  whole  body,  let  us  repeat,  should  be  kept  in  as 
good  condition  as  possible.  Bacteria  cannot  prey  upon 
vigorous  and  healthy  tissue,  and  if  the  organs  of  the 
body  they  may  attack  are  made  up  of  healthy  cells  and 
tissue  the  bacteria  soon  die  and  are  cast  out  of  the 
body.  Thus,  with  a  perfectly  healthy  body,  we  shall 
win  in  the  fight  without  even  knowing  that  we  have 
been  attacked. 

Importance  of  Increasing  Lung  Capacity. — An  unde- 
veloped chest  lessens  the  capacity  of  the  lungs.  Those 
parts  of  the  lungs  that  are  not  used  are  more  liable  to 
become  the  lodging  place  of  the  bacillus.  So  here, 
again,  deep  breathing  and  exercises  to  develop  the  chest 
and  lungs  are  important. 

Those  who  have  catarrh  of  the  nose  or  throat  should 
wash  these  parts  out  with  warm  salt  and  water  at  least 
twice  a  day.  This  will  keep  the  membranes  clean  and 
healthy  and  prevent  the  bacteria  from  finding  an  open- 
ing for  attack  there. 

How  to  Destroy,  the  Bacteria. — The  fact  that  the 
bacteria,  when  given  off  by  the  consumptive,  are  easily 
destroyed  by  exposure  to  sunlight,  or  heat,  makes  the 
problem  of  fighting  the  disease  much  simpler  than  if  the 
bacillus  usually  lived  and  multiplied  outside  the  body. 


286  PHYSIOLOGY  AND  HYGIENE 

But  the  bacillus  may  live  for  years  in  dark,  damp 
places,  or  in  undisturbed  corners.  It  is  in  this  way 
that  houses  in  which  consumptives  have  lived  become 
infected  and  are  breeding  places  for  the  disease,  lead- 
ing to  the  belief  that  the  disease  "  runs  in  the  family." 
In  rooms  which  have  been  occupied  by  a  consumptive 
the  walls  and  woodwork  should  be  scraped  and  scoured, 
repainted  and  repapered  and  the  floors  and  every  nook 
and  cranny  that  may  contain  dust  or  dirt,  scrubbed 
with  a  chloride  of  lime  mixture,  made  of  one  part  lime 
and  twelve  parts  water.  The  halls,  banisters,  and 
other  parts  of  the  house  should  also  be  cleaned  just  as 
thoroughly  as  possible.  Then  if  all  the  members  of 
the  consumptive's  family  will  devote  themselves  to 
building  up  healthy  bodies  there  will  no  longer  be  cause 
to  fear  the  i '  inherited ' '  disease. 

As  the  bacteria  are  carried  in  the  dust,  a  feather 
duster  or  a  dry  broom  should  never  be  used  in  cleaning 
a  room  occupied  by  a  patient,  as  they  only  stir  up  the 
dust  which  floats  about  in  the  air  and  settles  down 
again.  It  is  better  to  put  damp  paper  or  sawdust  on 
the  carpet  when  sweeping,  and  to  use  for  dusters  soft 
or  damp  cloths,  which  can  be  shaken  out  of  doors. 

Children  in  school  should  never  use  a  common  drink- 
ing cup.  The  other  children  may  be  quite  well  them- 
selves, but  some  one  in  their  homes  may  have  this  disease 
or  some  other  that  is  communicable,  and  in  that  case 
they  could  carry  the  bacteria  to  others. 


A   WAR   FOR   THE   NATION  287 

ALCOHOL  AND   CONSUMPTION 

The  best  physicians  agree  that  one  of  the  strongest 
allies  the  tubercle  bacillus  has  is  alcohol. 

In  the  cure  of  consumption  our  great  need  is,  as  we 
have  seen,  to  take  as  much  nourishment  as  possible  in 
order  to  build  up  the  tissues  and  counteract  the  power 
of  the  bacteria.  For  this  we  need  to  have  the  diges- 
tion in  the  best  possible  condition ;  and  it  is  important 
also  that  the  lungs,  so  actively  engaged  in  the  purify- 
ing of  the  blood,  should  not  be  hindered  in  their  work. 
Both  stomach  and  lungs  are  unfavorably  affected  by 
the  use  of  alcohol;  the  extent  of  the  injury  depending 
in  part  upon  the  amount  of  liquor  taken,  and  in  part 
upon  the  condition  of  these  organs. 

Any  appearance  of  a  good  effect  from  taking  alcohol 
is  deceptive,  and  if  we  need  further  proof  of  its  bad 
effects  we  find  from  statistics  that  there  is  a  larger 
proportion  of  tuberculosis  cases  among  those  who  drink 
than  among  non-drinkers. 

Tobacco,  also,  is  very  bad  for  consumptives,  and  for 
those  predisposed  to  the  disease,  as  it  may  weaken  the 
heart  and  thus  obstruct  the  circulation,  making  it  more 
difficult  for  the  lungs  to  resist  attack. 

PRECAUTIONS   FOR   CONSUMPTIVES 

The  following  simple  directions,  taken  from  a  cir- 
cular issued  by  the  Charity  Organization  Society  of 
New  York  City,  should  be  familiar  to  everyone,  as 
each  of  us  will  probably  at  some  time  in  his  life  come  in 


288  PHYSIOLOGY   AND   HYGIENE 

contact  with  someone  who  has  the  disease,  and  may, 
by  knowing  these  precautions  and  teaching  others  how 
to  take  them,  save  many  lives  in  this  great  national 
struggle. 

If  we  know  any  one  among  our  relatives  or  friends 
who  has  consumption  or  is  threatened  with  it,  we  could 
bear  our  share  in  the  fight  by  copying  these  directions 
for  them,  or  better  still,  by  writing  to  the  Charity  Or- 
ganization Society,  New  York  City,  for  copies  of  their 
circular  for  distribution  where  ihey  will  do  the  most 
good.  In  this  way  we  may  help  the  patients  them- 
selves to  get  well  and  protect  those  about  them. 

DIRECTIONS 

"  Consumption  can  often  be  cured  if  its  nature  be  recognized  early 
and  if  proper  means  be  taken  for  its  treatment.  In  a  majority  of 
cases  it  is  not  a  fatal  disease. 

"Consumptives  are  warned  against  the  many  widely  advertised 
cures,  specifics  and  special  methods  of  treatment  of  consumption.  No 
cure  can  be  expected  from  any  kind  of  medicine  or  method,  except  the 
regularly  accepted  treatment,  which  depends  upon  pure  air,  an  out-of- 
door  life  and  nourishing  food. 

"  Consumption  is  a  disease  of  the  lungs,  which  is  taken  from  oth- 
ers, and  is  not  simply  caused  by  colds,  although  a  cold  may  make  it 
easier  to  take  the  disease.  It  is  caused  by  very  minute  germs,  which 
usually  enter  the  body  with  the  air  breathed.  The  matter  which 
consumptives  cough  or  spit  up  contains  these  germs  in  great  num- 
bers— frequently  millions  are  discharged  in  a  single  day.  This  mat- 
ter, spit  upon  the  floor,  wall  or  elsewhere,  dries  and  is  apt  to  become 
powdered  and  float  in  the  air  as  dust.  The  dust  contains  the  germs, 
and  thus  they  enter  the  body  with  the  air  breathed.  This  dust  is 
especially  likely  to  be  dangerous  within  doors.  The  breath  of  a  con- 
sumptive does  not  contain  the  germs  and  will  not  produce  the  dis- 


A  WAR  FOR  THE  NATION  289 

ease.  A  well  person  catches  the  disease  from  a  consumptive  only  by 
in  some  way  taking  in  the  matter  coughed  up  by  the  consumptive. 

"It  is  not  dangerous  to  live  with  a  consumptive,  if  the  matter 
coughed  up  by  him  be  promptly  destroyed.  This  matter  should  not 
be  spit  upon  the  floor,  carpet,  stove,  wall  or  sidewalk,  but  always,  if 
possible,  in  a  cup  kept  for  that  purpose.  The  cup  should  contain 
water  so  that  the  matter  will  not  dry,  or  better,  carbolic  acid  in  a 
five  per  cent,  water  solution  (six  teaspoonfuls  in  a  pint  of  water). 
This  solution  kills  the  germs.  The  cup  should  be  emptied  into  the 
water  closet  at  least  twice  a  day,  and  carefully  washed  with  boiling 
water. 

"  Great  care  should  be  taken  by  consumptives  to  prevent  their 
hands,  face  and  clothing  from  becoming  soiled  with  the  matter 
coughed  up.  If  they  do  become  thus  soiled,  they  should  be  at  once 
washed  with  soap  and  hot  water.  Men  with  consumption  should 
weai  no  beards  at  all,  or  only  closely  cut  mustaches.  When  con- 
sumptives are  away  from  home,  the  matter  coughed  up  should  be 
received  in  a  pocket  flask  made  for  this  purpose.  If  cloths  must  be 
used,  they  should  be  immediately  burned  on  returning  home.  If 
handkerchiefs  be  used  (worthless  cloths,  which  can  be  at  once  burned, 
are  far  better),  they  should  be  boiled  at  least  half  an  hour  in 
water  by  themselves  before  being  washed.  When  coughing  or  sneez- 
ing, small  particles  of  spittle  containing  germs  are  expelled,  so  that 
consumptives  should  always  hold  a  handkerchief  or  cloth  before  the 
mouth  during  these  acts  ;  otherwise,  the  use  of  cloths  and  handker- 
chiefs to  receive  the  matter  coughed  up  should  be  avoided  as  much 
as  possible,  because  it  readily  dries  on  these,  and  becomes  separated 
and  scattered  into  the  air.  Hence,  when  possible,  the  matter  should  be 
received  into  cups  or  flasks.  Paper  cups  are  better  than  ordinary 
cups,  as  the  former  with  their  contents  may  be  burned  after  being 
used.  A  pocket  flask  of  glass,  metal,  or  pasteboard  is  also  a  most 
convenient  receptacle  to  spit  in  when  away  from  home.  Cheap  and 
convenient  forms  of  flasks  and  cups  may  be  purchased  at  many  drug 
stores.  Patients  too  weak  to  use  a  cup  should  use  moist  rags,  which 
should  at  once  be  burned.  If  cloths  are  used  they  should  not  be 
carried  loose  in  the  pocket,  but  in  a  water-proof  receptacle  (tobacco 


290  PHYSIOLOGY  AND  HYGIENE 

pouch),  which  should  be  frequently  boiled.  A  consumptive  should 
never  swallow  his  expectoration. 

"A  consumptive  should  have  his  own  bed,  and,  if  possible,  his 
own  room.  The  room  should  always  have  an  abundance  of  fresh  air 
—  the  window  should  be  open  day  and  night.  The  patient's  soiled 
wash-clothes  and  bed  linen  should  be  handled  as  little  as  possible 
when  dry,  but  should  be  placed  in  water  until  ready  for  washing. 

"  If  the  matter  coughed  up  be  rendered  harmless,  a  consumptive 
may  frequently  not  only  do  his  usual  work  without  giving  the  dis- 
ease to  others,  but  may  also  thus  improve  his  own  condition  and 
increase  his  chances  of  getting  well." 

FOOD  AND  EXERCISE 

The  first  articles  of  diet  for  a  consumptive  person 
should  be  milk  and  eggs  —  as  much  of  each  of  these  as 
he  can  be  prevailed  upon  to  consume.  The  eggs  may 
be  beaten  up  in  milk.  But  the  milk  and  egg  diet 
should  not  take  the  place  of  the  three  regular  meals. 
A  good  deal  of  meat  should  be  eaten,  also  vegetables 
and  fruit. 

Care  should  be  taken  in  exercising  not  to  use  up  the 
strength,  but  to  increase  the  amount  of  exercise  grad- 
ually. Rest  is  of  greater  importance. 

ANIMAL  TUBERCULOSIS 

When  it  was  discovered  that  dairy  cows  were  subject 
to  tuberculosis,  great  fear  was  felt  that  human  beings 
acquired  the  disease  from  the  milk  and  meat  of  diseased 
cattle.  But  cases  where  the  disease  is  carried  by  the 
milk  or  meat  are  rare  among  adults,  although  there  is 
danger  to  children  feeding  on  milk. 


CHAPTER   XVI 
PUBLIC   HYGIENE 

Private  and  Public  Hygiene. — We  study  physiology 
that  we  may  learn  how  to  live  healthy  lives;  and  the 
rules  by  which  we  should  guide  our  own  lives  constitute 
personal  hygiene.  But  there  are  problems  connected 
with  the  maintenance  of  health  which  it  is  impossible 
for  each  to  regulate  for  himself.  This  is  because  so 
many  people  live  together  in  towns  and  cities  where 
each  one  is  more  or  less  dependent  on  others.  Our 
scientific  men  have  learned  the  causes  of  many  diseases 
and  have  devised  methods  of  preventing  them.  To 
make  these  methods  effective,  the  condition  of  the  whole 
community  must  be  considered  in  any  preventive  meas- 
ures that  are  used.  For  the  purpose  of  safeguard- 
ing the  public  health  various  regulations  are  adopted 
for  the  whole  community.  These  constitute  public 
hygiene. 

BOARDS  OF  HEALTH  AS  PUBLIC  PROTECTORS 
Hidden  Dangers. — If  wild  beasts  were  to  run  in  our 
streets,  we  should  feel  that  we  had  a  right  to  demand 
that  the  officers  take  care  of  them;  but  there  are  in 
our  streets  sources  of  disease  more  dangerous  than  wild 
animals.  We  have  already  learned  that  some  diseases 
are  caused  by  microscopic  germs.  These  germs  we  can- 
not see.  Most  people  know  nothing  about  them,  not 

291 


292  PHYSIOLOGY  AND  HYGIENE 

even  where  they  are  found.  If  we  are  to  be  protected 
against  these  great  dangers,  it  must  be  by  obeying  the 
directions  of  some  who  understand  how  to  combat 
them.  We  have  a  right  to  demand  protection  against 
these  unseen  dangers  as  well  as  against  those  that  are 
seen. 

Boards  of  Health. — To  protect  the  public  from  these 
hidden  dangers,  Boards  of  Health  have  been  very  gen- 
erally established  by  law.  These  boards  are  usually  of 
two  kinds.  One,  a  State  Board  of  Health,  consists  of 
a  number  of  men  appointed  from  different  parts  of  the 
State.  The  duty  of  this  board  is  to  make  regulations 
for  the  whole  State  and  to  give  advice  to  the  different 
towns  and  cities  on  matters  relating  to  public  health. 
The  other,  a  city  or  town  Board  of  Health,  consists  of 
a  number  of  men,  including  one  or  more  physicians, 
whose  duty  it  is  to  see  that  the  proper  rules  for  the 
protection  of  the  public  are  carried  out  in  the  different 
towns  and  cities.  Besides  these,  there  are  Water 
Boards  whose  duty  it  is  to  guard  the  water  supply; 
milk  inspectors  to  watch  the  milk;  and  food  commis- 
sioners and  inspectors  to  see  that  only  proper  food  is 
offered  for  sale  in  the  markets.  Sometimes  there  are 
other  officers  whose  duty  it  is  to  look  after  other  mat- 
ters of  public  interest.  The  good  health  of  the  com- 
munity depends  primarily  upon  the  proper  regulation 
of  its  food,  water,  and  air,  and  upon  the  control  of 
contagious  diseases.  We  should  always  remember  that 
the  various  officers  who  have  these  matters  in  charge 
are  working  for  our  good. 


PUBLIC   HYGIENE 


293 


INSPECTION  OF  WATER,  VENTILATION,  AND   FOOD 

Water. — Disease  germs  are  sometimes  distributed  by 
water.  It  is  necessary  for  us  all  to  drink  water,  but  if 
our  drinking  water  contains  the  germs  of  typhoid  fever, 
it  is  very  dangerous.  In  the  country  we  can  guard  our 
own  well  or  spring  or  cistern,  but  in  a  town  or  city  we 


FIG.  92. — A  WELL  PROPERLY  LOCATED  WITH   REFERENCE   TO  THE 
WATERSHED. 

drink  the  water  that  is  supplied,  and  perhaps  do  not 
even  know  its  source.  We  cannot  discover  either  by 
looking  at  water  or  by  tasting  it  whether  it  is  whole- 
some or  dangerous.  Hence,  in  well-governed  cities 
and  towns,  it  is  the  duty  of  the  "Water  Commissioners 
to  guard  the  public  water  supply  for  all  citizens.  Such 
Commissioners  try  to  secure  for  us  a  sufficient  supply 
of  pure  water  and  to  guard  the  supply  from  pollution. 
The  most  dangerous  material  that  can  get  into  water 
is  sewage,  and  no  water  that  has  sewers  emptying  into 


294 


PHYSIOLOGY   AND   HYGIENE 


it  is  fit  to  drink.  Hence  a  community  should  if  possible 
take  its  drinking  water  from  some  other  source  than 
rivers,  for  these  are  almost  sure  to  receive  sewage  from 
other  cities  and  towns  on  their  banks.  For  a  similar 


FIG.  93. — AN  UNHEALTHFUL  LOCATION  FOR  A  WELL. 

reason,  too,  the  Water  Commissioners  frequently  fence 
in  the  reservoirs  in  order  to  keep  people  away  from 
them  and  thus  protect  them  from  the  dirt  and  filth 
that  would  be  dangerous  to  all  drinking  the  water. 

"When  a  community  is  compelled  to  get  its  water  sup- 
ply from  a  river  or  any  other  source  that  is  contaminated 


PUBLIC  HYGIENE  295 

with  sewage,  the  Commissioners  try  to  devise  some 
method  of  filtering  the  water  that  shall  remove  the 
disease  germs,  or  some  method  of  rendering  them  harm- 
less. This  filtering  must  be  done  on  a  large  scale  and 
according  to  scientific  methods.  We  know  that  the 
small  filters  that  are  used  in  houses  are  seldom  more 
than  good  strainers.  They  may  separate  from  the 
water  particles  of  dirt  and  vegetable  matter,  but  they 
do  not  exclude  the  dangerous  disease  germs.  What  we 
have  learned  about  the  minute  size  of  such  germs  will 
serve  to  explain  this. 

If  the  water  supply  is  not  properly  filtered^  the 
Commissioners  often  advise  boiling  it  in  order  to  de- 
stroy the  disease  germs.  The  most  important  means 
of  protecting  the  water  is  to  prevent  all  forms  of 
excrement  and  decaying  matter  from  getting  into  the 
water  supply.  Money  spent  in  improving  the  water 
supply  yields  great  returns  in  increasing  the  healthful- 
ness  of  the  community. 

Fresh  Air. — We  have  already  learned  how  necessary 
it  is  to  our  health  that  we  should  have  an  abundance  of 
clean,  fresh  air;  but  many  people  do  not  appreciate 
this,  and  they  and  their  friends  suffer  in  consequence. 
In  rooms  made  almost  air-tight  by  keeping  the  windows 
and  doors  closed,  the  air  becomes  foul  and  is  sure  to 
be  loaded  with  germs,  some  of  which  are  likely  to  be 
dangerous  to  breabhe.  In  such  rooms  we  breathe,  over 
and  over  again  the  poisonous  gases  and  bacteria,  and 
much  evil  necessarily  results.  Many  people  do  not 
understand  this,  and  in  order  to  keep  warm  and  to  save 


296  PHYSIOLOGY  AND   HYGIENE 

money,  they  live  and  sleep  crowded  together,  several 
in  a  room,  without  ventilation.  Under  these  condi- 
tions they  " catch"  diseases  from  one  another  by 
contact  and  breathing  the  germs  in  the  impure  air. 

Such  homes  are  dangerous  not  only  to  the  occupants, 
but  to  all  who  live  in  the  neighborhood,  for  the  disease 
germs  from  them  are  sure  to  be  scattered  widely.  We 
have  a  right  to  demand  protection  from  such  dangers, 
and  our  public  officials  sometimes  find  it  necessary  to 
enter  such  homes  and  insist  on  better  conditions.  In 
some  cases  this  arouses  much  opposition  to  the  health 
officers,  for  the  occupants  of  such  homes  may  feel  that 
their  rights  are  being  interfered  with.  But  they  have 
no  more  right  to  breed  disease  in  this  way  than  they 
would  have  to  breed  ferocious  wild  animals  and  turn 
them  loose  on  the  community. 

In  the  same  way,  public  hygiene  demands  good  ven- 
tilation in  school  rooms,  factories,  work-rooms,  stores, 
public  halls,  and  in  all  places  where  many  people  live 
together.  Plenty  of  fresh,  pure  air  wherever  people 
congregate  is  an  important  public  safeguard. 

Foods. — Pure  foods  are  no  less  needed  than  pure  air. 
In  trying  to  get  rich  quickly,  some  dealers  mix  with  the 
food  they  sell  cheap  materials  of  little  or  no  food  value. 
Water  is  put  into  milk,  ground  beans  into  coffee.  Many 
other  foods,  such  as  flours,  spices,  teas,  etc.,  are  fre- 
quently adulterated.  It  is  well  to  remember  that  pre- 
pared foods  are  most  likely  to  be  thus  adulterated,  and 
there  is  more  danger  in  the  cheaper  grades  than  in 
those  costing  a  little  more.  Cheap  canned  goods  are 


PUBLIC  HYGIENE  297 

not  really  cheap,  for  we  are  likely  to  buy  in  them  a 
considerable  proportion  of  worthless  material. 

Sometimes  the  manufacturers  put  into  food  substances 
that  are  actually  harmful.  There  are  kinds  of  food  that 
will  not  keep  well  for  any  length  of  time,  and  to  preserve 
them  certain  chemicals  are  sometimes  used.  These  are 
called  preservatives.  Those  most  generally  used  are 
borax,  salicylic  acid,  and  formalin.  These  are  all  mild 
poisons,  and  their  constant  use  in  foods  is  harmful. 
Meats,  fish,  milk  and  canned  goods  are  most  frequently 
treated  with  these  preservatives.  Here  again  it  is  the 
cheaper  grades  that  are  most  likely  to  be  thus  ' ( pre- 
served ' ' ;  the  better  grades  are  safer  and  cheaper  in  the 
long  run. 

It  is  usually  impossible  for  us  to  know  by  examina- 
tion or  taste  whether  our  foods  are  pure  or  whether 
they  are  adulterated  and  "  preserved."  This  matter, 
therefore,  is  left  to  public  officials.  Pure  food  laws 
make  it  a  crime  to  treat  food  in  these  ways,  and  trained 
inspectors  can  thus  protect  us  from  fraud  and  dangers 
that  we  should  not  otherwise  know. 

PREVENTION  OF  CONTAGIOUS  DISEASES 
Garbage  and  Sewage. — Every  household  produces  a 
quantity  of  refuse  material  that  is  both  unpleasant  and 
dangerous.  There  is  the  garbage,  or  waste  from  our 
kitchens  and  our  tables.  There  is  also  the  sewage 
consisting  of  excrement  and  other  secretions  from  our 
bodies.  The  latter  is  dangerous,  especially  if  there  is 
a  sick  person  in  the  family.  In  earlier  centuries  such 


298 


PHYSIOLOGY  AND   HYGIENE 


waste  was  thrown  into  the  streets  or  gutters,  or  else 
allowed  to  soak  into  the  soil  until  that  became  saturated 
with  filth.  When  we  remember  that  all  this  material 
is  likely  to  contain  disease  germs,  we  can  easily  under- 
stand that  such  disposition  of  it  was  not  only  unsightly 


FIG.  94. — DIAGRAM  OF  HOUSE  AND  STREET  CONNECTIONS  WITH  THE 
CITY  SEWERS. 

and  unpleasant,  but  dangerous  as  well.  Epidemics  used 
to  sweep  through  such  cities  and  people  were  constantly 
dying  from  preventable  germ  diseases.  Indeed,  in 
many  cities  people  then  died  faster  than  children  were 
born,  and  but  for  the  flocking  of  the  country  people 
to  them,  these  cities  would  have  disappeared  from,  the 
map. 


PUBLIC  HYGIENE  299 

Our  modern  cities  have  learned  to  take  care  of  those 
forms  of  waste  that  breed  disease.  Garbage  is  required 
to  be  placed  in  cans  furnished  by  the  householder,  and 
the  waste  from  them  is  regularly  removed  by  garbage 
wagons.  Our  streets  are  filled  with  large  underground 
tunnels  called  sewers,  and  into  these  all  of  the  more 
offensive  materials  from  our  homes  are  conducted  and 
are  washed  along  in  them  by  water  from  our  sinks  and 
closets,  and  by  rain  from  the  gutters.  This  mass  of 
water  washes  the  material  out  of  the  city,  where  it  is 
disposed  of  in  some  way,  and  thus  the  city  is  kept  sweet 
and  clean.  To  make  these  sewerage  systems  of  real  use, 
each  house  should  be  properly  connected  with  them. 
Hence  the  need  of  careful  plumbing.  If  there  are 
leaks  in  pipes  connecting  our  sinks  and  closets  with  the 
sewers,  the  danger  from  disease  germs  is  great.  A 
careful  inspection  of  plumbing  is  thus  necessary  for 
health. 

In  many  cities  people  are  now  prohibited  from  throw- 
ing papers  or  any  other  refuse  matter  into  the  streets; 
they  are  required  to  put  it  into  receptacles  provided  at 
certain  places  on  the  streets  for  the  purpose.  Most 
cities  forbid  spitting  in  the  street  cars,  and  some  forbid 
it  on  the  sidewalks,  for  this  habit  is  not  only  filthy  and 
unsightly,  but  is  likely  to  distribute  disease  germs. 
The  result  of  these  improvements  is  very  noticeable. 
Not  only  are  our  cities  becoming  sweeter,  cleaner,  and 
more  attractive  places  to  live  in,  but  they  are  also  be- 
coming more  healthful. 


300  PHYSIOLOGY  AND   HYGIENE 

PROTECTION   FROM   CONTAGIOUS  DISEASES 

The  Spread  of  Contagious  Diseases. — There  are  some 
diseases,  as  explained  in  Chapters  XIII  and  XIV, 
that  pass  from  person  to  person.  When  one  has  such 
a  disease  the  germs  that  produce  them  are  constantly 
leaving  his  body.  If  another  person  remains  near  the 
patient  the  germs  may  be  taken  into  his  body,  and 
then  he  may  have  the  disease.  Diseases  that  may  be 
contracted  in  this  way  we  call  contagious.  The  diseases 
most  commonly  distributed  in  this  way  are  smallpox, 
diphtheria,  scarlet  fever,  measles,  mumps,  and  whoop- 
ing-cough. If  people  mingle  freely  with  each  other  a 
single  case  of  such  a  disease  is  likely  to  spread  and  to 
cause  an  epidemic.  Schools  may  distribute  contagious 
diseases  not  only  when  the  sick  children  go  to  school, 
but  also  when  the  brothers  and  sisters  of  a  sick  child 
are  allowed  to  attend  school,  for  they  may  carry  the 
disease  germs  in  their  clothes. 

To  prevent  the  distribution  of  contagious  diseases  is 
one  of  the  most  important  duties  of  the  health  officers. 
Yarious  rules  for  isolation  have  been  devised.  Isola- 
tion means  simply  keeping  the  patient  away  from  those 
who  are  liable  to  take  the  disease  from  him.  A  child 
who  has  a  contagious  disease  should  never  be  allowed 
to  attend  school,  and  should  always  be  kept  in  a 
room  by  himself,  away  from  all  members  of  the  family 
except  the  one  who  nurses  him.  In  the  more  severe 
contagious  diseases,  such  as  smallpox,  scarlet  fever  and 
diphtheria,  where  the  chances  of  contagion  are  great, 
the  patient  is  frequently  taken  to  a  special  hospital 


PUBLIC   HYGIENE  301 

where  he  can  be  more  carefully  attended  and  where 
there  is  no  chance  of  his  spreading  the  disease.  He  is 
thus  kept  away  from  others  until  he  has  so  completely 
recovered  that  he  can  no  longer  give  the  disease,  the 
length  of  time  being  determined  by  physicians. 

Treatment  of  Infected  Objects.  — Anything  that  comes 
in  contact  with  a  patient  may  become  infected  with  the 
germs  of  disease,  and  unless  properly  cared  for,  may  be 
the  means  of  spreading  the  infection.  This  applies  to 
excretions  from  his  body,  and  also  to  clothing,  bedding, 
towels,  handkerchiefs,  knives,  forks,  drinking  cups, 
books,  toys,  food  left  by  the  patient,  etc.  Before  such 
objects  should  be  handled  by  others,  the  germs  upon 
them  must  be  destroyed,  or,  as  we  say,  the  article  must 
be  disinfected.  All  articles  of  little  value,  like  bits  of 
cloth,  toys,  and  food,  should  be  destroyed.  Others 
may  be  made  safe  in  several  ways. 

It  is  most  important  to  understand  fully  that  simple 
boiling  is  quite  sufficient  to  destroy  any  dangerous 
germs  that  are  likely  to  be  left  on  clothing,  towels, 
bedding,  handkerchiefs,  eating  utensils,  etc.  While 
some  bacteria  produce  spores  that  are  not  killed  by 
simple  boiling,  none  of  the  germs  of  the  common 
diseases  do  so.  Any  infected  article,  therefore,  that 
can  be  placed  in  a  boiler  with  water  and  boiled  for 
fifteen  minutes  to  half  an  hour,  will  be  rendered  per- 
fectly safe,  since  this  kills  all  common  disease  germs. 
Steam  will  do  the  same,  if  it  can  be  applied  to  objects 
in  closed  vessels  and  so,  too,  will  the  dry  heat  of  an  oven. 

Objects  which  cannot  be  boiled  may  sometimes  be 


302  PHYSIOLOGY  AND   HYGIENE 

soaked  or  washed  in  a  disinfectant.  These  disinfect- 
ants are  solutions  which  contain  chemicals  that  kill 
germs  quickly.  They  are  all  poisonous,  should  always 
be  labeled  POISON,  handled  with  care,  and  never  taken 
into  the  mouth.  The  best  of  them  are  the  following  : 

Formalin.  —  Formalin  is  a  liquid  which  looks  like 
water,  but  is  a  powerful  disinfectant.  Any  article 
soaked  in  a  2%  to  4%  solution  will  be  thoroughly 
disinfected,  and  is  no  more  injured  by  the  formalin 
than  it  would  be  by  soaking  in  water.  If  formalin 
stands  in  the  open  air,  it  gives  off  a  gas  very  irritating 
to  the  eyes.  This  gas  is  the  real  disinfecting  agent, 
and  health  officers  frequently  use  it  to  disinfect  a  room 
after  it  has  been  occupied  by  a  patient  with  a  conta- 
gious disease  (as  explained  on  page  304). 

Corrosive  Sublimate.  —  Corrosive  sublimate  is  in- 
tensely poisonous.  One  part  of  it  dissolved  in  one 
thousand  parts  of  water  forms  a  powerful  disinfectant. 
It  may  be  bought  in  tablets,  eight  of  which  dissolved 
in  a  gallon  of  water  give  the  desired  strength.  It 
may  be  used  for  washing  floors,  furniture,  or  walls  of 
rooms,  or  for  disinfecting  excreta  which  should  be 
allowed  to  soak  in  the  disinfectant  an  hour.  It  must 
not  be  used  on  metals,  since  it  injures  them.  In 
strength  of  1  part  corrosive  sublimate  to  2000-4000 
parts  water,  it  may  be  used  to  disinfect  wounds. 

Chloride  of  Lime.  —  Chloride  of  lime,  or  bleaching 
powder,  is  a  cheap  and  very  good  disinfectant.  One 
pound  dissolved  in  eight  gallons  of  water  gives  the 
desired  strength.  It  can  be  used  just  like  corrosive 


PUBLIC   HYGIENE  303 

sublimate  and  allowed  to  act  an  hour  or  more.  It  is 
not  so  violently  poisonous  as  corrosive  sublimate,  and 
does  not  injure  metals. 

Carbolic  Acid.  —  Carbolic  acid  is  one  of  the  best  and 
most  widely  used  disinfectants.  It  must  not  be  used  full 
strength,  one  part  of  the  acid  in  twenty  of  water  being 
the  right  proportion  for  most  purposes.  It  is  rather 
costly,  and  for  ordinary  disinfection  of  rooms  or  excreta 
is  not  so  good  as  the  cheaper  disinfectants.  The  fact 
that  it  has  a  strong  odor  does  not  make  it  of  any  more 
value  as  a  disinfectant.  A  2  %  to  5  %  solution  can  be 
used  upon  the  flesh  to  disinfect  wounds. 

In  the  use  of  any  disinfectant  it  should  be  remem- 
bered that  the  object  must  be  actually  wet  with  the 
disinfectant.  Pouring  a  little  on  the  floor  of  a  room, 
or  allowing  it  to  stand  in  an  open  vessel,  is  of  no  value 
whatsoever,  even  though,  like  carbolic  acid,  it  has  a  strong 
odor.  The  odor  has  no  power  of  destroying  the  germs. 

Care  of  the  Sick  Room.  —  The  health  officers  also  per- 
form a  very  important  service  in  caring  for  the  room  in 
which  a  patient  has  been  ill  with  some  contagious 
disease.  After  the  recovery  of  the  patient,  the  bacteria 
that  cause  the  disease  are  generally  still  present  in  the 
room ;  indeed,  some  of  these  germs  live  for  many 
months  in  dark  corners  or  in  clothing  if  no  attempt  is 
made  to  destroy  them.  Hence  it  is  very  important  that 
a  room  and  its  furnishings,  which  may  probably  con- 
tain large  numbers  of  such  dangerous  germs,  should 
be  thoroughly  cleansed  and  all  the  bacteria  there  de- 
stroyed before  it  is  used  again.  This  the  health  officers 


304  PHYSIOLOGY  AND   HYGIENE 

undertake  to  do;  the  process  is  called  fumigation  or 
disinfection. 

A  common  method  is  first  to  make  the  room  as  near 
air-tight  as  possible  by  stuffing  all  the  cracks  with 
cotton,  or  better,  pasting  strips  of  paper  over  all  places 
where  air  may  enter ;  then  a  large  quantity  of  some 
germ-destroyer  is  burned  in  the  room,  which  is  left 
closed  for  twenty-four  hours. 

Hospitals. — As  an  aid  in  the  treatment  of  disease, 
our  modern  cities  have  built  hospitals.  Here  the  best 
of  care  and  medical  attendance  is  given  to  the  sick.  So 
carefully  are  the  hospitals  managed  that  the  patient  has 
usually  much  greater  chance  of  speedy  recovery  there 
than  if  he  remains  at  home.  Patients  are  cared  for  at 
small  expense,  and  frequently  no  charge  is  made  to 
those  who  cannot  afford  to  pay. 

QUESTIONS 

1.  What  do  we  mean  by  personal  hygiene  ? 

2.  What  do  we  mean  by  public  hygiene  ? 

3.  Why  do  cities  have  Boards  of  Health  ? 

4.  Name  some  officials  who  care  for  the  health  of  the  public? 

5.  How  may  the  drinking  water  become  impure  ? 

6.  Explain  the  importance  of  fresh  air. 

7.  Why  do  we  have  food  inspectors? 

8.  How  should  garbage  and  sewage  be  disposed  of? 

9.  How  can  we  avoid  taking  or  spreading  contagious  diseases  ? 

10.  Name  four  good  disinfectants. 

11.  How  may  the  bacteria  in  a  sick  room  be  destroyed? 


CHAPTER   XVII 
WHAT   TO   DO   IN    EMERGENCIES 

THEKE  are  many  times  when  a  knowledge  of  what 
to  do  in  ease  of  accident  may  be  of  great  advantage 
and  occasionally  such  knowledge  may  be  the  means  of 
saving  life. 

Some  important  emergencies  have  already  been  men- 
tioned on  various  pages  of  this  book : 

Broken  bones. — See  page  132. 

Burns. — See  page  177. 

Dislocations. — See  page  140. 

Drowning. — See  page  120. 

Foreign  bodies  in  the  eye. — See  page  221. 

Freezing. — See  page  178. 

Sprains. — See  page  140. 

TOOTHACHE 

Toothache  is  always  a  warning  that  the  teeth  need 
attention.  In  many  cases  a  cavity  will  be  found  in  the 
aching  tooth,  and  in  this  case  the  pain  may  be  stopped 
for  a  time  by  twisting  up  a  bit  of  cotton,  dipping  it 
in  oil  of  cloves  and  inserting  it  into  the  cavity.  All 
cavities  in  the  teeth  should  be  filled,  for  they  serve  as 

lodging  places  for  troublesome  bacteria. 

305 


306  PHYSIOLOGY  AND  HYGIENE 

NOSEBLEED 

Nosebleed  is  usually  not  serious  and  will  soon  stop 
of  itself.  The  head  should  be  held  erect  and  not  bent 
over  a  basin.  The  pinching  of  the  nostrils  will  some- 
times hasten  the  clotting  of  the  blood  so  as  to  stop 
the  bleeding.  If  it  continues  persistently,  ice  (wrapped 
in  a  towel  for  convenience),  applied  to  the  back  of 
the  neck  and  the  bridge  of  the  nose,  will  frequently 
check  it.  Sometimes  it  may  be  necessary  to  put  a 
plug  of  cotton  in  the  nose.  While  the  bleeding  con- 
tinues, and  for  some  time  afterwards,  one  should  not 
blow  the  nose  nor  cough  if  avoidable,  since  it  is  likely 
to  start  the  bleeding  afresh,  by  breaking  away  the 
clots  that  are  closing  the  broken  blood  vessels. 

CHOKING 

A  solid  object  passing  through  the  throat  may  become 
lodged  in  one  of  the  smaller  passages  below,  producing 
choking,  If  something  gets  into  the  windpipe  so  as 
to  prevent  the  passage  of  air  into  the  lungs,  a  violent 
fit  of  coughing  starts  at  once  and  the  irritating  object 
will  be  blown  out  with  the  blast  of  air,  unless  it  is  too 
firmly  lodged.  Unless  it  is  quickly  removed,  however, 
the  person  will  die. 

Large  objects  do  not  often  get  stuck  in  the  windpipe. 
It  is  more  common  for  them  to  get  lodged  in  the  gullet, 
where  they  are  less  immediately  dangerous,  since  they 
do  not  prevent  breathing.  They  must  be  removed, 
however,  and  the  best  thing  to  do  is  to  have  the  person 


WHAT   TO   DO   IN  EMERGENCIES  307 

bend  his  body  forward  over  a  chair  and  then  to  slap 
him  on  the  back  between  the  shoulders.  The  danger 
in  choking  is  so  great  that  one  should  never  allow 
himself  to  carry  in  his  mouth  small  objects,  like  buttons, 
pins,  tacks,  beads,  marbles,  etc.  This  is  a  particularly 
dangerous  thing  to  do  when  one  is  running. 

CRAMPS 

Cramps  is  the  name  given  to  a  violent  contraction  of 
the  muscles,  usually  of  the  legs  or  arms,  that  renders 
them  stiff,  so  that  for  the  while  one  cannot  move  them. 
The  trouble  is  most  likely  to  occur  when  one  has  been 
for  some  time  in  cold  water,  and  hence  frequently 
attacks  swimmers.  If  it  occurs  when  one  is  in  deep 
water  and  no  help  is  at  hand,  even  a  good  swimmer  is 
likely  to  drown,  since  he  cannot  move  his  muscles  and 
becomes  helpless  and  faint  from  pain.  It  is  not  safe 
therefore  to  swim  into  deep  water  unless  some  one  is 
near  by  who  can  aid  if  the  swimmer  is  seized  with 
cramps.  The  longer  one  is  in  the  water  the  more 
likely  is  he  to  have  cramps.  The  trouble  comes  on 
very  quickly  and  does  not  last  long,  though  the  muscles 
may  be  sore  for  a  day  or  two.  Although  most  common 
when  one  is  swimming,  one  may  have  cramps  at  any 
time.  Nothing  needs  to  be  done,  for  the  trouble  soon 
disappears. 

STINGS    OF   INSECTS 

An  insect  such  as  a  bee.,  hornet,  wasp  or  yellow 
jacket  wounds  by  thrusting  into  the  skin  a  sharp, 
needle-like  sting  which  carries  with  it  a  very  irritating 


308 


PHYSIOLOGY  AND   HYGIENE 


poison.     In  the  case  of  most  insects  the  sting  is  smooth 

and  can  be  at  once  withdrawn  so  that  the  animal  can 

sting  again.  The  sting  of  the 
honeybee  is  barbed  and  cannot 
be  removed  from  the  wound, 
but  is  pulled  out  of  the  body  of 

FIG.  95.  — A  BUMBLE  BEE.    the    bee  when   it    flies   away. 

The  sting  may  then  be  seen  still  in  the  wound  and 

should  be  removed  by  forceps  or  the  point  of  a  knife. 

The  pain  is  produced  by 

the  poison,  and  since  this 

is  an  acid  poison  an  alka- 
line remedy  is  best.  Soda 

or  ammonia  applied   to 

the    spot    is    good,  but 

nothing  is  really  better  FIG.  96. -A  WASP. 

than  wet  mud,  which  will  soon  relieve  the  pain.     If 

insects  are  let  alone  they  will  not  sting.  When  they 

light  on  flowers  one  is  hold- 
ing, or  upon  some  sweet 
food,  if  allowed  quietly  to 
feed  upon  it,  they  will  soon 
fly  away  without  stinging. 

If  one  grows  excited  and  tries  to  strike,  then  they  will 

get  angry  and  sting. 

SNAKE    BITES 

Many  people  have  a  great  fear  of  snake  bites.  While 
it  is  true  that  some  snakes  have  a  poisonous  bite,  this 
danger  is  one  of  the  rarest,  a  far  lesser  danger  than 


FIG.  97. — A  HONEYBEE. 


WHAT  TO  DO  IN  EMERGENCIES  309 

playing  with  matches  or  teasing  dogs.  Poisonous 
snakes  are  not  common  in  this  country  and  not  found 
at  all  in  settled  localities.  Aside  from  a  rare  species 
found  in  Mexico,  there  are  only  three  kinds  here  that 
are  really  poisonous  :  the  rattlesnake,  the  water  moc- 
casin, and  the  copperhead.  All  others  are  harmless,  in 
spite  of  various  stories  to  the  contrary. 

In  biting,  the  harmful  snake  forces  a  very  violent 
poison  into  the  flesh,  which  is  soon  carried  over  the  body 
through  the  circulation.  The  first  thing  to  do  is  to  tie  a 
handkerchief  around  the  limb  that  is  bitten,  above  the 
bite,  and  then  insert  a  stick  inside  the  handkerchief, 
twisting  the  stick  so  as  to  compress  the  blood  vessels  and 
stop  the  flow  of  blood.  This  will  prevent  the  poison 
from  flowing  with  the  blood  over  the  body.  The  wound 
should  then  be  sucked  to  remove  as  much  of  the  poison 
as  possible.  The  poison  does  no  injury  in  the  mouth  and 
no  harm  to  the  person  who  sucks  it,  if  care  is  taken  to 
empty  the  mouth  at  once.  If  the  wound  does  not  bleed, 
it  should  be  cut  open  to  induce  bleeding.  It  is  necessary 
to  proceed  quickly,  since  every  moment  is  precious. 

POISONING   FROM   IVY   AND    POISON   DOGWOOD 

Poison  ivy  and  sumac  produce  an  oily  secretion  that 
is  poisonous  to  most  people  if  it  gets  on  the  skin. 
Poison  ivy  is  a  common  vine,  growing  over  rocks  and 
stone  walls  or  climbing  up  trees.  Its  leaf  is  waxy  in 
the  spring,  glossy  green  in  the  summer,  and  scarlet  in 
the  fall.  It  resembles  somewhat  the  harmless  and  beau- 
tiful woodbine,  or  Virginia  creeper,  but  may  be  easily 


310 


PHYSIOLOGY   AND  HYGIENE 


distinguished  by  the  fact  that  it  has  three  leaflets,  while 
the  woodbine  has  five.  It  has  yellowish  green  berries, 
while  the  woodbine  has  dark  blue  berries. 

The  poison  dogwood,  or  sumac,  is  a  shrub  growing 
chiefly  in  swamps.  It  has  leaves  each  with  eleven  to 
thirty-one  leaflets  and  produces  loose  clusters  of  white 

berries.  The  beautiful 
flowering  dogwood 
should  not  be  confused 
with  it.  This  grows  on 
dry  ground,  has  leaves 
of  seven  to  thirteen 
leaflets  and  dark  red 
fruit,  and  is  perfectly 
harmless.  The  poison 
of  the  dogwood  is  more 
severe  than  that  of  the 
ivy. 
FIG.  98.  — THE  LEAVES  OF  THE  WOOD-  When  one  has  been 

BINE    AND    THE    POISON   IVY.  once       poisoned       he       IS 

more  likely  to  be  poisoned  a  second  time.  The  poison 
is  of  an  oily  nature  and  may  be  removed  by  thorough 
washing  with  soap  and  water.  If  one  acquires  the  habit 
of  thoroughly  washing  the  hands,  arms,  face,  and  neck 
with  warm  soap  and  water  immediately  after  coming  from 
a  tramp  in  the  woods  or  fields,  he  will  usually  be  able  to 
avoid  the  poisoning  from  these  plants,  since  it  takes 
several  hours  or  sometimes  a  day  or  two  before  the  poison 
can  do  any  injury.  The  poisoning  shows  itself  by  an 
intense  itching,  swelling,  and  blistering  of  the  skin,  and 


WHAT  TO  DO  IN  EMERGENCIES  311 

is  sometimes  very  disagreeable.  It  wears  off  in  a  few 
days,  and  in  the  meantime  there  is  no  better  remedy 
than  plain  soap  and  water. 

ACCIDENTS   FROM   ELECTRICITY 

Electricity  is  a  useful  friend,  but  may  be  dangerous 
if  one  is  not  careful.  A  large  wire  used  for  light- 
ing purposes  or  for  running  trolley  cars  may  contain  a 
current  of  a  power  high  enough  to  kill  any  one  who 
allows  it  to  pass  through  his  body.  A  wire  with  a 
current  in  it  is  called  a  "  live  wire,"  arid  is  dangerous 
to  handle ;  indeed,  if  the  current  is  a  powerful  one, 
even  touching  the  wire  would  mean  instant  death. 

One  should  never  touch  a  loose  wire  attached  to  an 
electric  circuit,  and  unless  one  has  definite  knowledge 
to  the  contrary  all  wires  attached  to  electric  poles  should 
be  considered  dangerous  to  touch.  Sometimes  a  live 
wire  is  seen  lying  with  its  loose  end  in  the  street  or  on 
the  sidewalk,  and  some  one  thoughtlessly  trying  to  kick 
it  aside  gets  a  fatal  shock.  Electricity  will  not  pass 
through  rubber,  dry  silk,  or  dry  paper,  and  if  one  picks 
up  the  wire  with  rubber  gloves,  a  rubber  overshoe,  or 
a  thick  mass  of  newspapers  the  electricity  will  not  touch 
him.  If  these  objects  are  wet,  however,  they  will  let 
the  electricity  pass  and  give  the  shock  to  the  person 
trying  to  pick  up  the  wire.  If  one  picks  up  the  end 
of  a  wet  rope  or  kite  string  lying  on  a  live  wire,  it  may 
convey  the  electricity  to  him. 

If  a  person  gets  tangled  up  in  a  wire  with  a  current 
not  strong  enough  to  kill  him  at  once,  it  may  burn  him 


312  PHYSIOLOGY   AND   HYGIENE 

badly.  He  is  unable  to  free  himself,  for  the  electricity 
makes  it  impossible  for  him  to  use  his  muscles.  An- 
other person  must  loose  him,  handling  the  wire  with 
rubber  or  absolutely  dry  material.  Burns  made  by 
electricity  are  slower  in  healing,  but  they  should  be 
treated  like  other  burns. 

SUNSTROKE  AND  HEAT  PROSTRATION 

Although  sunstroke  and  heat  prostration  are  both 
due  to  excessive  heat,  they  are  different,  and  have  to  be 
treated  differently.  Sunstroke  is  due  to  the  direct  rays 
of  the  sun  shining  upon  one's  head  on  excessively  hot 
days.  It  is  to  be  avoided  by  protecting  the  head  from 
the  sun  by  an  umbrella  or  a  broad  hat,  or  by  keeping  in 
the  shade.  A  person  who  has  sunstroke  becomes  dizzy, 
and  perhaps  unconscious,  and  his  skin  will  be  found  to 
be  hot  and  dry.  He  should  be  removed  to  the  nearest 
shade  and  placed  in  a  sitting  posture  against  a  tree  or 
some  other  support.  His  clothing  should  be  loosened, 
cold  water  poured  over  his  head,  or  his  body  rubbed 
with  bits  of  ice.  If  he  can  swallow,  he  should  be  given 
cool  drinks,  but  never  alcoholic  stimulants. 

Heat  prostration  may  be  caused  by  excessive  heat 
away  from  the  direct  rays  of  the  sun,  as  in  a  hot  engine 
room,  for  example.  The  person  will  be  pale  and  faint, 
but  his  skin  will  not  be  hot  and  feverish.  He  should 
be  removed  to  the  nearest  cool  spot,  placed  flat  on  his 
back,  his  clothing  loosened,  and  his  hands  and  feet 
rubbed  to  restore  circulation.  The  face  and  body 
should  be  bathed  in  warm  water,  and  warm  cloths 


WHAT   TO   DO   IN   EMERGENCIES  313 

should  be  applied  to  his  body.     Warm  drinks  may  be 
given. 

In  all  cases  a  physician  should  be  summoned  as  soon 
as  possible.  A  person  who  has  once  been  prostrated 
by  heat  is  more  subject  to  a  second  attack,  and  needs 
afterwards  to  be  particularly  careful  not  to  expose  him- 
self to  heat. 

POISONS 

The  treatment  to  be  followed  when  one  swallows 
poison  varies  with  the  kind  of  poison.  There  are  a 
few  general  rules  always  applicable.  1.  Act  promptly, 
for  the  delay  of  even  a  few  minutes  may  make  the  dif- 
ference between  recovery  and  death.  2.  Send  for  a 
physician  immediately.  3.  Until  the  physician  comes, 
cause  the  patient  to  vomit.  4.  Administer  an  antidote 
to  the  poison. 

Induce  immediate  vomiting,  so  as  to  remove  as  much 
as  possible  of  the  poison  from  the  stomach.  This  may 
be  done  by  giving  a  teaspoonful  of  powdered  mustard 
in  a  glass  of  warm  water.  After  the  mustard  has  been 
swallowed,  tickle  the  back  part  of  the  throat  with  the 
finger  or  a  feather.  If  vomiting  does  not  occur  at  once, 
repeat  the  dose  in  about  ten  minutes.  Common  salt 
will  sometimes  serve  in  the  place  of  mustard  if  the 
latter  is  not  at  hand. 

Administer  some  antidote  to  counteract  the  effect  of 
the  poison  which  remains  in  the  body.  The  antidote 
to  be  used  depends  upon  the  poison.  The  most  com- 
mon poisons  and  their  antidotes  are  given  below.  In 


314  PHYSIOLOGY  AND  HYGIENE 

their  treatment  vomiting  should  be  induced,  unless 
otherwise  stated. 

Acid  poisons,  like  sulphuric  acid  (oil  of  vitrol),  nitric 
acid  (aqua  fortis),  muriatic  acid,  oxalic  acid,  carbolic 
acid,  etc.  In  these  cases  the  vomiting  should  be  omitted, 
and  three  or  four  spoonfuls  of  soda  or  of  baking 
powder  should  be  given  to  neutralize  the  acid.  The 
whites  of  three  or  four  eggs,  limewater,  or  even  soap- 
suds may  also  be  used.  Oxalic  acid  and  carbolic  acid, 
even  when  neutralized,  remain  poisonous.  The  services 
of  a  physician  are  needed  to  wash  out  the  stomach. 

Alkali  poisons  like  ammonia,  potash,  or  lye  should  be 
created  with  an  acid  to  neutralize  the  alkali.  Vinegar 
and  water,  or  lemon  juice,  giving  all  the  person  can 
drink,  constitutes  the  antidote. 

Arsenic  is  an  ingredient  of  paris  green,  many  fly 
powders,  and  green  paints.  Mix  some  tincture  of  iron 
with  baking  powder  and  give  the  patient  a  spoonful 
of  the  brownish  powder  which  appears,  or  use  the  white 
of  eggs.  Administer  every  minute  or  two. 

Lead  is  found  in  sugar  of  lead,  white  lead  used  by 
painters,  tinfoil  of  tobacco  coverings,  etc.  Administer 
a  strong  solution  of  Epsom  salts  or  Glauber's  salts. 

Mercury  is  found  in  corrosive  sublimate,  used  for 
various  purposes,  chiefly  as  a  disinfectant.  Omit  try- 
ing to  induce  vomiting  and  administer  the  white  of 
an  egg,  or  flour  beaten  up  with  milk  or  water. 

Opium  is  found  in  laudanum,  paregoric,  soothing  sirups, 
cholera  mixtures,  etc.  Give  strong  coffee  or  aromatic 
spirits  of  ammonia  (fifteen  drops  of  the  ammonia  every 


WHAT   TO   DO   IN   EMERGENCIES  315, 

few  minutes).  Use  all  means  to  keep  the  patient  mov- 
ing and  to  prevent  his  sleeping. 

Strychnine.  —  Use  chloroform  or  ether  to  relieve  the 
violent  spasms.  Aromatic  spirits  of  ammonia  or  bro- 
mide of  sodium  may  be  used,  five  grains  of  the  latter 
every  half  hour.  Artificial  respiration  may  be  neces- 
sary. 

Phosphorus.  —  Children  sometimes  suck  the  heads  off 
matches.  Common  matches  contain  phosphorus,  which 
is  a  poison.  The  treatment  for  phosphorus  before  the 
doctor  comes  is  to  induce  vomiting  and  then  to  give 
the  patient  the  white  of  an  egg  followed  by  Epsom 
salts. 

The  after-treatment  for  poisoning  must  be  such  as  to 
combat  dangerous  symptoms  which  have  arisen.  This, 
however,  must  be  left  to  a  physician,  and  cannot  be 
done  without  special  knowledge  of  medicine. 

*      QUESTIONS 

1.  Why  should  you  keep  the  cavities  in  your  teeth  well  filled? 

2.  How  may  a  nosebleed  be  checked  ? 

3.  What  should  you  do  if  some  one  is  choking  from  having 
some  object  lodged  in  his  throat? 

4.  How  should  the  sting  of  a  bee  be  treated  ? 

5.  How  may  you  prevent  ivy  poisoning  ? 

6.  How  may  a  "live  "  electric  wire  be  handled? 

7.  How  should  you  treat  a  case  of  heat  prostration  ?    Of  sun- 
stroke?    How  tell  the  difference  between  them  ? 

8.  What  is  the  first  thing  to  do  when  one  has  swallowed  poison  ? 


CHAPTER   XVIII 
HOW  TO   DEVELOP  OUR   BODIES 

Introductory. — While  we  are  learning  about  the 
different  parts  of  the  body  we  should  not  forget  that 
the  object  of  all  this  study  is  to  learn  how  to  care  for 
the  body  as  a  whole,  and  we  should  consider  what  we 
may  do  to  keep  it  at  its  best,  working  easily  and  to 
advantage.  In  the  chapters  on  "  Eespiration, "  "The 
Muscles,"  and  " The  Blood"  there  are  references 
to  exercise,  to  breathing,  and  to  the  uniform  develop- 
ment of  all  the  muscles;  let  us  in  this  chapter  look 
especially  into  the  practical  side  of  the  matter. 

It  is  easy  to  learn  what  we  should  do,  but  unless  we 
take  the  time  and  trouble  to  practice  what  we  learn, 
regularly  and  thoroughly,  we  cannot  expect  to  get 
much  benefit. 

We  must  remember,  too,  that  the  most  wonderful 
of  those  bodily  changes  and  actions  that  take  place 
day  after  day  do  not  happen  on  the  surface  of  the  body, 
where  we  might  see  and  feel  them.  Because  this  is  true 
we  are  inclined  to  think  that  breaking  the  laws  of  health 
is  harmless  if  we  feel  no  ill  effects  from  such  mistakes. 
That,  however,  is  as  foolish  as  it  would  be  for  us  to  think 
that  the  sun  stopped  shining  on  a  cloudy  day  just  be- 
cause we  were  unable  to  see  it.  We  cannot  make  our 

316 


HOW  TO  DEVELOP  OUR  BODIES  317 

feelings  a  test  of  the  physical  effects  of  our  actions;  nor 
can  we  expect  to  see  or  to  feel  any  extraordinary  ben- 
efit when  we  begin  to  follow  carefully  the  rules  of  health 
which  we  have  been  taught,  or  to  take  systematic  exer- 
cise, as  will  be  suggested  in  this  chapter.  Still  we  may 
be  sure  that  in  these  ways  we  shall  certainly  be  adding 
to  our  strength  and  to  the  power  of  our  bodies ;  and  in 
time  the  effects  will  be  evident. 

Importance  of  Developing  the  Body. — The  muscular 
system  is  developed  by  work  and  by  exercise;  both  are 
necessary  to  our  health  and  therefore  to  our  usefulness 
and  happiness.  Our  bodies  are  the  means  by  which  we 
accomplish  all  that  we  have  to  do  in  this  world,  and 
unless  they  are  strong  and  each  organ  does  its  part 
well,  we  cannot  expect  to  accomplish  what  we  wish. 
Good  work  is  impossible  without  good  bodies. 

Necessity  of  Work  and  Exercise. — Why  is  it  that  peo- 
ple after  they  are  grown  frequently  lose  the  good  health 
that  they  had  when  they  were  children?  Usually  they 
give  some  parts  of  their  bodies  plenty  of  work  to  do, 
but  they  do  not  give  the  whole  body  systematic  exer- 
cise and  healthful  recreation. 

Perhaps  as  boys  and  girls  they  were  not  taught  a  few 
simple  facts  which  everyone  should  know  with  regard 
to  the  care  of  the  body  and  how  to  exercise  it  in  order 
to  strengthen  and  develop  all  its  parts.  It  is  true  that 
most  boys  and  girls  get  a  great  deal  of  out-of-door  ex- 
ercise in  their  sports  and  games,  and  thus  keep  some  of 
the  muscles  strong  and  well;  but  something  more  than 
this  is  needed. 


318  PHYSIOLOGY  AND   HYGIENE 

Dangers  of  Unequal  Development. — Perfect  health  re- 
quires that  all  the  muscles  be  developed  uniformly,  but 
our  games  and  sports,  as  a  rule,  influence  only  certain 
sets  of  muscles,  often  at  the  expense  of  others.  Even 
athletes  may  have  consumption  or  heart  trouble,  be- 
cause in  training  particularly  the  muscles  they  wish  to 
use,  they  neglect  the  training  that  is  necessary  to  de- 
velop equally  the  strength  of  the  lungs — not  the  chest 
muscles  only — and  the  heart;  two  most  important 
organs  of  the  body,  upon  which  the  proper  working 
of  all  the  others  depends. 

In  addition  to  our  games,  we  need,  therefore,  to 
practice  exercises  by  which  each  part  of  the  body  shall 
receive  a  reasonable  share  of  attention  and  be  developed 
in  proportion  to  its  usefulness  and  needs. 

Relation  of  Oxygen  to  Muscular  Effort. — When  we 
exercise  a  muscle  vigorously  it  requires  more  nourish- 
ment, and  for  this  oxygen  is  the  first  essential  (page 
116).  As  we  must  secure  the  oxygen  by  drawing  the 
air  into  the  lungs,  exercises  which  will  help  us  to  breathe 
more  deeply  and  thus  take  more  oxygen  into  the  sys- 
tem should  receive  most  careful  consideration. 

BREATHING 

Deep  Breathing. — To  breathe  deeply,  then,  is  the  first 
rule  to  be  observed  in  healthful  exercise.  We  must 
first  understand  the  importance  of  breathing  through 
the  nose  (page  105).  Even  in  violent  exercise  there  are 
seldom  conditions  that  properly  admit  of  mouth  breath- 
ing. The  fact  that  certain  forms  of  vigorous  exercise 


HOW  TO   DEVELOP  OUR  BODIES  319 

compel  us  to  fill  and  empty  the  lungs  frequently,  shows 
us  one  of  the  reasons  why  they  are  beneficial. 

Significance  of  Yawning  and  Stretching. — Nature  tries 
to  meet  this  necessity  for  oxygen  in  many  ways;  one 
of  them  is  by  giving  us  the  desire  to  yawn  and  stretch 
when  we  are  tired  or  have  been  sitting  still  for  a  long 
time.  People  frequently  discourage  this  habit  in  chil- 
dren because  it  "  looks  lazy",  but  when  we  consider 
that  it  relieves  the  muscles  and  organs  of  the  body  from 
a  cramped  or  strained  position,  and  at  the  same  time 
fills  the  lungs  with  a  fresh  supply  of  oxygen,  we  can 
see  that  this  is  really  a  valuable  exercise,  though  one 
that  cannot  be  taken  at  all  times  and  in  all  places. 
When  we  feel  like  stretching,  it  is  well  to  take  some 
light  form  of  exercise  to  relieve  the  strain  and  fatigue 
against  which  the  body  is  protesting. 

Since,  however,  it  is  necessary  in  performing  these 
exercises  that  our  bodies  be  in  a  correct  position,  it  is 
very  important  that  we  should  first  learn  to  know  when 
the  body  is  in  proper  poise. 

Sitting. — Yery  few  of  us  know  how  to  sit  or  stand 
properly,  and  yet  the  correct  position  of  the  body  is 
the  basis  for  all  our  physical  development. 

We  think  it  is  more  comfortable  and  restful  to  lounge 
down  in  our  seats  or  lean  upon  our  desks  at  school,  or 
to  sit  in  rocking  chairs  at  home,  but  as  a  matter  of  fact 
such  positions  are  in  the  end  weakening  and  tiresome. 
Why?  Because  in  these  positions  the  chest  is  con- 
tracted so  that  it  is  impossible  to  get  the  proper  amount 
of  air  into  the  luogs,  and  the  organs  of  the  abdomen  are 


320  PHYSIOLOGY  AND  HYGIENE 

pressed  together  or  out  of  position,  so  that  they  cannot 
work  freely.  All  these  things  cause  a  strain  on  the 
bocty  which  does  not  exist  if  we  sit  erect,  with  the  body 
comfortably  poised,  and  give  each  organ  plenty  of  space 
and  nourishment. 

So,  if  you  would  keep  your  strength  and  secure  the 
proper  development  of  your  bodies,  learn  first  of  all  to 
sit  erect. 

Standing. — If  we  do  not  stand  erect  the  organs  of  the 
trunk — the  lungs,  heart,  stomach,  etc. — have  not  suffi- 
cient room,  and  so  cannot  perform  their  functions  prop- 
erly, causing  unnecessary  fatigue  and  sometimes  actual 
discomfort. 

Then,  too,  we  must  consider  the  force  of  gravitation, 
which  is  continually  drawing  objects  toward  the  earth. 
If  we  stand  erect,  our  bodies  are  well  balanced;  that 
is,  the  force  is  distributed  evenly;  while  if  we  stoop 
forward  there  is  a  strain  that  we  constantly  resist,  which 
causes  us  to  grow  tired  sooner  than  otherwise. 

Poise. — For  a  graceful,  well-balanced  poise,  we  should 
stand  with  the  legs  straight,  head  erect,  chin  drawn 
slightly  in,  and  chest  high,  and  with  the  weight  chiefly 
on  the  balls  of  the  feet.  Too  frequently  we  stand  with 
the  weight  on  the  heels,  the  hips  coming  forward  and 
the  abdomen  thrust  forward.  Watch  some  day  the 
people  you  meet,  and  see  what  proportion  of  them  stand 
in  this  way.  Compare  the  ease  and  grace  of  those 
who  stand  with  the  body  properly  poised.  Faulty 
poise  is  not  to  be  corrected  by  drawing  the  abdomen  in 
and  holding  it  back  tensely.  This  is  not  necessary  if 


HOW  TO   DEVELOP   OUR  BODIES  321 

the  proper  balance  of  the  body  is  secured  as  indicated 
above.  Further,  it  is  an  unwise  way  of  correcting  the 
fault,  as  the  muscles  of  the  abdomen  should  be  left  free 
to  expand  and  contract  naturally;  and  this  may  be 
accomplished  without  allowing  the  abdomen  to  be 
thrust  forward. 

The  chest  should  not  be  thrown  too  far  forward ;  this, 
however,  is  not  a  common  fault  in  position.  A  good 
rule  to  follow  is  to  stand  in  such  a  way  that  the  lips, 
chin,  outer  line  of  the  chest,  and  the  tips  of  the  toes 
are  in  a  straight  line.  A  long  pole  or  fishing  rod  held 
vertically  against  the  front  of  the  body  may  be  used  to 
test  the  position. 

The  balance  of  the  body  may  be  tested  by  a  simple 
little  exercise.  Stand  squarely  on  both  feet  in  the  posi- 
tion that  is  most  natural  to  you.  Then  carry  the  weight 
forward  to  the  toes;  carry  it  back  to  the  heels,  and 
finally  to  the  balls  of  the  feet ;  resting  there.  Compare 
this  position  with  the  natural  one  you  first  assumed. 
You  will  probably  discover  that  you  are  accustomed  to 
stand  with  the  weight  too  near  the  heels. 

BREATHING   EXERCISES 

The  Process  of  Breathing. — Before  we  think  of  special 
breathing  exercises  for  the  development  of  the  body, 
let  us  see  what  is  said  in  Chapter  Y  about  the  proc- 
ess of  breathing  or  respiration.  We  read  how  air 
is  drawn  into  the  lungs  largely  through  the  action 
of  the  muscular  wall  called  the  diaphragm,  which  by 
moving  downward  increases  the  size  of  the  chest  cavity, 


322  PHYSIOLOGY  AND  HYGIENE 

thus  causing  the  air  to  enter  the  lungs  to  fill  the  en- 
larged space.  Its  upward  motion  by  decreasing  the  same 
cavity,  causes  the  air  to  leave  the  lungs,  as  there  is  not 
then  room  for  so  much  air.  While  all  this  happens 
easily  and  regularly,  we  are  probably  hardly  conscious 
even  of  the  fact  that  we  are  breathing ;  we  usually  have 
no  sensation  from  the  motion  of  the  diaphragm,  and 
the  upward  and  outward  movement  of  the  ribs  during 
respiration  is  likewise  unnoticed. 

Necessity  of  Deep  Breathing. — The  important  point 
is  that  the  lungs  should  be  well  filled  with  fresh  air, 
and  this  frequently.  In  ordinary  breathing  we  expand 
the  top  of  the  lungs,  while  the  lower  part  of  them  may 
be  inactive,  not  doing  its  proper  duty  toward  purifying 
the  blood  and  enriching  it  with  oxygen.  So  our  prob- 
lem is  to  set  all  portions  of  oar  lungs  to  work.  If  you 
find  that  your  abdomen  does  not  move  in  and  out 
noticeably  as  you  breathe,  call  a  halt  and  see  whether 
you  are  not  letting  the  upper  part  of  your  lungs  do 
work  that  ought  to  be  done  by  the  lower  lungs,  aided 
by  the  ribs  and  the  diaphragm. 

In  the  beginning  we  may  have  to  think  about  it  every 
time  we  take  a  long  breath,  and  perhaps  shall  forget  the 
deep  breathing  unless  we  are  reminded;  bat  if  we  per- 
sist, we  can  finally  form  the  habit,  and  when  this  is 
done,  it  will  be  sure  proof  that  we  have  greatly  in- 
creased our  strength  and  our  power  of  endurance. 

The  following  exercises  are  recommended  by  several 
well-known  experts  in  physical  training,  prominent 
among  whom  is  Dr.  Claes  J.  Enebuske,  from  whose 


HOW  TO  DEVELOP  OUR  BODIES 


323 


" Progressive  Gymnastic  Day's  Orders"  '  many  valu- 
able suggestions  have  been  drawn.  They  are  so  sim- 
ple that  they  may  be  taken  at  home  without  any  super- 
vision; the  pupil  who  practices  them  regu- 
larly, night  and  morning,  will  certainly  find 
a  gain  in  his  strength  and  in  muscle  control. 
Exercise  i. — Stand  erect,  heels  together, 
toes  out,  hands  down  at  side.  Draw  a  deep 
breath  slowly,  and  at  the  same  time  raise  the 
arms  slowly  from  the  sides  until  the  palms 
nearly  meet  over  the  head,  as  shown  in  Fig- 
ure 99.  Lower  the  arms  gradually,  exhaling 
slowly.  Eepeat  each  of  these  exercises  about 
eight  times. 

Exercise  2. — Stretch  the 
arms  straight  out  in  front 
of  the  body,  palms  facing. 
Keeping  the  arms  in  a  hor- 
izontal position  (see  Fig. 
100),  move  them  slowly  backward, 
and  see  how  near  you  can  come  to 
bringing  the  hands  together  at  the 
back,  without  bending  or  lowering 
the  arms.  Inhale  and  exhale  as 
before. 

Exercise  3. — Arms  straight  out  in 
front,  palms  down.  Raise  the  arms 
slowly  over  the  head,  then  as  far  back  as  possible, 

1  The  illustrations  used  in  this  chapter  are  taken  from  the  same 
book.     Published  by  Silver,  Burdett  &  Company. 


FIG.  99. 


FIG.  100. 


324  PHYSIOLOGY  AND  HYGIENE 

down,  and  to  original  position,  making  in  this  way  a 
sort  of  crooked  circle  in  the  air  with  the  hands.  In- 
hale slowly  as  the  arms  are  raised,  and  exhale  as  they 
are  lowered. 

To  vary  these  exercises  from  time  to  time,  instead  of 
exhaling  as  the  arms  descend,  hold  the  breath  until 
the  arms  are  in  their  original  position.  Then  exhale 
very  slowly. 

WALKING 

Having  learned  to  stand  correctly,  and  to  breathe 
deeply,  we  must  next  learn  how  to  walk  in  such  a  way 
as  to  make  the  best  possible  use  of  our  muscles,  and 
gain  strength  and  endurance. 

Probably  a  majority  of  people  rest  their  weight  as 
they  step  more  on  the  heel  than  on  the  forward  part 
of  the  foot.  This  is  not  right.  As  each  foot  touches 
the  ground  the  weight  should  be  thrown  upon  the  ball 
of  the  foot,  and  as  it  leaves  the  ground  pressure  should 
be  exerted  upon  the  same  part  and  upon  the  toes.  This 
will  carry  the  body  forward  easily,  and  the  movement 
when  once  acquired  will  enable  one  to  walk  much  more 
rapidly  and  with  less  fatigue.  It  also  develops  the 
muscles  of  the  foot  and  ankle,  and  of  the  lower  part  of 
the  leg. 

The  Indians,  and  athletes  who  are  trained  for  walk- 
ing long  distances,  use  this  method.  At  first  it  should 
be  practiced  for  only  a  few  minutes  at  a  time,  as  one  is 
using  muscles  that  are  not  accustomed  to  the  work, 
and  so  tire  quickly.  But  when  one  comes  to  realize  the 


HOW  TO  DEVELOP  OUR  BODIES 


325 


delightful  ease  of  motion  which  is  secured  in  this  way, 
he  will  think  the  lesson  was  well  worth  while. 

Deep  breathing  as  we  walk  adds  very  much  to  our 
feeling  of  buoyancy  and  ease  in  motion. 

When  we  have  learned  to  sit,  stand,  and  walk  cor- 
rectly, we  shall  have  formed  the  valuable  and  necessary 
foundation  for  the  correct  performance  of  all  other  phy- 
sical exercises. 

EXERCISES  FOR   SUPPLENESS— EASE   OF  MOTION 

Power  of  endurance  and  skill  in  the  use  of  the  body 
depend  very  largely  upon  ease  of  motion.  We  usually 
think  of  farmers  and  other  out-of-door  laborers  as  types 
of  strong  men.  But  frequently  we 
notice  that  they  are  awkward  and  stiff 
in  their  movements,  and  clumsy  in 
the  use  of  their  hands;  any  exercise 
to  which  they  are  not  accustomed  soon 
tires  them.  This  is  because  their  work 
compels  them  to  use  only  certain  sets 
of  muscles.  The  muscles  which  are 
not  used  get  stiff  and  do  not  respond 
readily  when  the  brain  orders  them 
to  move. 

So,  to  acquire  ease  of  motion,  we 
must  practice  exercises  to  keep  all  the 
muscles  flexible. 

Stand  erect,  hands  on  hips  (see  Fig.  101). 
Keeping  the  legs  straight,  bend  forward  from  the 
waist  until  the  upper  part  of  the  body  is  parallel 


FIG.  101. 


Exercise  4. 


326 


PHYSIOLOGY  AND   HYGIENE 


FIG.  102. 


with  the  floor,  then  back  as  far  as 
possible.  Return  slowly  to  an  erect 
position. 

Exercise  5. — Same  position.  Bend 
the  body  from  the  waist,  first  to  one 
side  then  to  the  other,  as  shown  in 
Figure  102. 

Exercise  6. — Stand  as  before,  rise  on 
tiptoe,  then  bend  the  knees,  letting  the 
body  sink  quickly,  then  up,  still  on 
tiptoe,  and  back  to  position  again. 
The  body  and  head  must  be  kept  erect 
in  this  exercise.  These  exercises  are 
also  valuable  in  strengthening  the  muscles  of  the 
abdomen  and  waist. 

Dancing  is  excellent  for  giving  flexibility 
and  grace. 


DEVELOPMENT  EXERCISES 
FOR  THE  ARMS 

Exercise  7  —  Stand  with 
hands  on  shoulders,  as  in 
Figure  103.  Thrust  arms 
quickly  out  sideways  and 
back  to  position,  then 
straight  up  and  back.  Re- 
peat  four  times. 

Exercise  8.  —  Arms  out 
at  sides,  palms  up.  Bend  elbows,  as 
shown  in  Figure  104.  Thrust  one 


103. 


FIG.  104. 


HOW   TO   DEVELOP  OUR  BODIES  327 

arm  out  to  full  length,  at  the  same  time  bending  the 
other  so  that  the  hand  strikes  the  shoulder.  Repeat, 
the  arms  bending  and  straightening  alternately. 

These  arm  movements  may  be  varied  by  using  light 
dumb-bells  or  other  objects  of  about  the  same  weight. 
As  the  strength  increases  the  weight  may  be  increased. 

Exercises  on  the  bars  and  rings  are  especially  good 
for  the  development  of  the  arms,  and  any  boy  who  can- 
not go  to  a  gymnasium  can  rig  up  a  single  bar  or  pair 
of  rings  at  his  own  home. 

Bar  or  Ring  Exercise. — Grasp  the  bar  or  rings  firmly, 
letting  the  body  hang  perfectly  straight,  feet  together. 
Draw  the  body  up  by  the  hands  until  the  chin  is  on  a 
level  with  the  hands.  As  the  muscles  grow  stronger 
it  will  be  possible  to  bring  the  breast  on  a  level  with 
the  hands. 

FOR  THE   SHOULDERS,   BACK   AND   CHEST 
Exercise  9. — Arms  hanging  loosely  at  the  sides.    Raise 
the  right  shoulder,  throw  it  forward,  down,  back,  up, 
thus    describing    a    circle.      Repeat   with    the    other 
shoulder.     Then  circle  in  the  opposite  direction. 

Exercise  10- — Arms  straight  out  at  sides,  palms  front. 
Swing  the  whole  arm  from  the  shoulder,  each  hand  thus 
describing  a  circle  in  the  air. 

Exercise  n. — Arms  over  right  shoulder  as  if  holding 
a  bat.  Left  foot  forward.  Fling  arms  and  body  for- 
ward and  down  as  if  striking  very  hard  at  something 
on  the  ground.  Repeat  with  arms  over  left  shoulder, 
right  foot  forward. 


328  PHYSIOLOGY   AND  HYGIENE 


FOR  THE  NECK 

Exercise  12. — Body  erect.  Bend  head  forward  and 
back  several  times,  then  to  the  right  and  left. 

Exercise  13. — Koll  the  head  around,  circling  first  to 
the  right,  then  to  the  left. 

FOR  THE   HANDS   AND   WRISTS 

Exercise  14. — Arms  straight  out  at  sides,  palms  down. 
Bend  the  wrists,  throwing  hands  as  far  back  as  possible, 
then  down.  Repeat  several  times. 

Exercise  15. — Keeping  wrist  and  back  of  hand  level, 
fingers  straight,  bend  fingers  down  from  the  knuckles, 
then  back  as  far  as  they  will  go. 

Exercise  16. — Relax  the  muscles  of  hands  and  fingers, 
and  letting  the  hands  droop  from  the  wrists,  shake  them 
until  they  are  thoroughly  relaxed;  as  the  hands  are  con- 
tinually employed  in  grasping  things,  the  muscles  are 
generally  contracted,  and  they  should  be  frequently 
relaxed. 

FOR  WAIST  AND  ABDOMINAL  MUSCLES 

All  exercises  that  involve  bending  from  the  waist  are 
good.  We  have  found  several  of  these  in  the  section 
on  suppleness. 

Exercise  17- — Stand  with  feet  slightly  apart.  Roll 
the  body  from  the  waist,  describing  a  circle  in  the  air 
with  the  head.  Circle  in  the  opposite  direction. 

Exercise  18. — Stand  with  feet  apart,  arms  straight 


HOW  TO  DEVELOP  OUR  BODIES 


329 


above  the  head.  Bend  forward  from  the  waist  until 
the  body  takes  almost  the  position  of  an  inverted  V, 
as  in  Figure  105. 

Exercise  19  —  Stand  with  hands 
on  hips.  Take  a  long  step  forward, 
bearing  the  weight  on  the  forward 
foot  (see  Fig.  106).  Back  to  posi- 
tion. Repeat  with  the  other  foot 
forward. 

FOR  THE  LEGS 


FIG.  105. 


Exercise  20.  —  For  strengthening 
eg  below   the  knee  and  de- 
veloping the  calf,  stand  erect,  and 
rise  and  sink  slowly  on  toes  and  heels  a  great  many 
times  (see  Fig.  107). 

Exercise  21.  —  Stand  on  one  foot  and  raise  the  other 
leg,  bending  the  knee  (see  Fig.  108).  Bend  and 
straighten  several  times.  Repeat  with  the  other  leg. 

Exercise  22  —  An  excellent  exercise  for  the  legs  and 
body  muscles  is  to  place  one 
foot  forward  as  if  stepping. 
Then  rising  on  the  toes,  spring 
lightly  back  and  forth,  alter- 
nating the  position  of  the 
feet. 

GAMES   AND   SPORTS 
The  great  value  of  games 
and  sports,    aside  from  the  '  FIG.  106. 


330 


PHYSIOLOGY   AND   HYGIENE 


pleasure  we  take  in  them  and  the  muscular  development 
they  give,  is  in  the  training  of  the  senses  and  the  mind. 
We  learn  to  think  quickly  and  to  be  alert  in  our  move- 
ments. We  also  come  to  see  how  important 
it  is  to  be  fair  in  our  treatment  of  others. 

Since  each  game  or  sport  trains  only  cer- 
tain sets  of  muscles,  and  requires  its  own 
particular  kind  of  effort,  it  is  well  to  be 
familiar  with  a  variety  of  such  pastimes. 

Running  is  especially  good  for  strengthen- 
ing the  muscles  of  the  legs ;  it  also  compels 
us  to  breathe  deeply. 

Jumping  develops  the  legs  and  the  ab- 
dominal muscles,  and  also  the  muscles  of 
the  shoulders  and  chest. 

Baseball  combines  all  the  good  qualities  of 
these  two  sports. 

Swimming  is  perhaps  the  most  val- 
uable sport  of  all,  for  it  exercises  a 
great  many  different  sets  of  muscles. 
All  strokes  should  be  practiced,  and 
also  swimming  on  the  back.  Every 
boy  and  girl  should  know  how  to 
swim,  not  only  because  it  is  good 
exercise,  but  so  that  in  case  of  acci- 
dents, which  occur  very  frequently 
on  the  water,  one  could  save  himself 
or  rescue  others  from  danger. 

Tennis — Tennis  exercises  the  legs 
and  ankles,  and  also  the  muscles  of  FIG.  108. 


FIG.  107. 


HOW  TO   DEVELOP  OUR  BODIES  331 

the  body,  but  the  right  arm  is  likely  to  be  developed  at 
the  expense  of  the  left.  In  striking  the  ball,  a  long  easy 
swing  of  the  arm  should  be  cultivated.  Handling  the 
racquet  gives  excellent  exercise  to  the  wrist. 

Skating.  —  Skating  is  almost  as  good  for  exercise  as 
swimming.  It  not  only  gives  exercise  to  the  muscles 
of  the  legs,  but  in  the  long,  sweeping  "strokes"  the 
muscles  of  the  waist  and  abdomen  are  brought  into 
constant  use.  The 
arms  help  in  keep- 
ing the  balance, 
and  the  vigorous 
exercise  in  the 

cold,   bracing    air  .       I] 

makes  one  breathe  ^%  J? 


deeply  and  so  de-  ^ 

velop    the    lungs 
and     chest.       Ice 

hockey   is    a    good  FlG>  109>  _  HAMMER  THROWING. 

skating  game,  al- 
though hockey,  of  course,  can  be  played  in  a  field  as 
well  as  on  the  ice. 

Hammer  throwing  and  shot  putting  are  two  excellent 
sports.  We  cannot  explain  the  scientific  points  here, 
but  perhaps  a  few  directions  will  show  how  these  sports 
develop  the  muscles. 

Hammer  Throwing. — The  thrower  must  stand  in  a 
circle  seven  feet  in  diameter,  feet  apart,  body  bent  for- 
ward and  well  balanced.  The  head  of  the  hammer 
(a  stick  with  a  heavy  weight  fastened  to  the  end  may 


332  PHYSIOLOGY  AND   HYGIENE 

be  substituted)  should  rest  on  the  ground  back  of  the 
thrower.  The  weight  of  the  hammer  should  not  be 
so  great  as  to  strain  the  arms  and  shoulders.  It  is 
better  to  start  with  a  light  hammer  and  increase  the 
weight  from  time  to  time. 

Shot  Putting.  —  The  player  stands  in  a  ring  as  before, 
left  foot  forward  and  weight  resting  on  the  right  foot. 
The  shot  (a  large,  smooth  stone  will  do)  held  up  in  the 
right  hand,  the  right  elbow  being  bent  so  that  the  upper 
arm  rests  against  the  side.  When  ready  to  throw,  slide 
the  left  foot  forward  quickly  and  back,  then  fling  the 
whole  right  side  forward  as  the  shot  is  thrown. 

ALCOHOL  AND  ATHLETICS 

Men  who  are  being  trained  for  athletic  contests  are 
forbidden  by  their  trainers  to  use  alcoholic  drinks, 
smoke  cigarettes,  or  use  tobacco  in  any  form,  because 
these  stimulants  and  narcotics  affect  the  action  of  the 
heart  and  prevent  the  contestants  from  carrying  on 
sustained  muscular  effort.  Alcohol  in  excess  interferes 
with  the  heart  and  the  circulation  of  the  blood  and 
impairs  the  action  of  the  digestive  organs.  It  also 
weakens  one's  moral  powers. 

Inhaling  the  smoke  of  cigarettes  not  only  may  cause 
heart  trouble,  but  prevents  proper  growth  of  the  body 
and  lowers  the  resistant  powers  to  disease.  Therefore, 
if  a  boy  wishes  to  be  strong  in  body  and  alert  in  mind 
he  should  be  like  the  athlete  in  training,  using  neither 
alcohol  nor  tobacco. 


GLOSSARY  OF  TECHNICAL  TERMS 

ab-do'mgn.  —  The  lower  cavity  of  the  body  containing  the  stomach, 

intestine,  and  other  organs. 

ab's?ess.  —  A  sore  that  comes  to  a  head  and  discharges  pus. 
S-dul'ter-a'tion.  —  The  debasing  of  a  product  by  the  addition  of  an 

impurity. 

51-bu'men.  —  A  proteid,  like  the  white  of  egg. 
Sn-te'ri-Qr  root.  —  The  branch  of  a  spinal  nerve  that  carries  messages 

from  the  brain  to  the  muscles.     See  Fig.  67. 

Sn'ti-dote.  —  Anything  that  will  counteract  the  effects  of  a  poison. 
an'ti-sep'tic.  —  A  substance  capable  of  destroying  germs. 
an'-ti-tQx'm.  —  A  substance   which   neutralizes  poison  produced  by 

germs. 

a-or'ta.  —  The  artery  carrying  blood  from  the  heart.     See  Fig.  21. 
a'que-ous  hu'mfir.  —  One  of  the  transparent  liquids  in  the  eye.     See 

Fig.  75. 
ar-te'ri-al  blood.  —  Blood  that  has  been  purified  by  passing  through  the 

lungs. 
ar'ter-y.  —  A  blood  vessel  carrying  blood  away  from  the  heart. 


.  —  One  type  of  bacteria. 
bac-te'ri-a.  —  A  group  of  very  minute  plants. 
ball-and-s5ck'£t  joint.  —  A  joint  allowing  free  motion  in  all  directions. 

See  Fig.  53. 

biceps.  —  The  front  muscle  of  the  upper  arm.     See  Fig.  65. 
bi-cus'pids.  —  Eight  of  the  teeth,  four  in  each  jaw,  between  the  canines 

and  the  molars.     See  Fig.  9. 
bile.  —  The  liquid  secreted  by  the  liver. 

blSd'der.  —  The  sac  that  temporarily  holds  the  kidney  secretion. 
blood  heat.  —  The  ordinary  temperature  of  the  body,  98.5°  F. 
bow'els.  —  The  intestine. 

breast  bone'.  —  The  bone  in  front  of  the  chest.     See  Fig.  42. 
brQn'chi.  —  The  branches  of  windpipe  entering  the  lungs.    See  Fig.  33. 


334  PHYSIOLOGY  AND  HYGIENE 

cal-los'i-ties.  — Parts  of  the  epidermis  thickened  by  friction. 
ca'nmes.  —  Four  teeth,  just  back  of  the  incisors.     See  Fig.  9. 
cap'il-la-ries. — The  small  blood  vessels  connecting  the  arteries  with 

the  veins.     See  Fig.  25. 
car'bfln  di-Qx'ide.  — The  gas  that  results  from  the  burning  of  carbon  in 

oxygen. 

car-5t'id.  —The  large  artery  in  the  neck.     See  Fig.  22. 
car'pals.  —  The  wrist  bones.     See  Fig.  42. 
car'ti-lage.  — The  tough  flexible  material  that  forms  the  softer  part  of 

the  skeleton.     See  Figs.  33,  42,  60. 
ca'se-m.  —  A  proteid  in  milk,  the  basis  of  cheese. 
ca-tarrh'. —  A  disease  of  the  nasal  cavity  and  throat. 
cau'ter-ize.  —  To  burn,  usually  for  the  purpose  of  destroying  infectious 

material. 
$§11.  —  One  of  the  microscopic  bits  of  living  matter  of  which  the  whole 

body  is  composed. 
ge're-als.  — Food  materials  obtained  from  grain,  such  as  wheat,  oats, 

rice,  etc. 

$er'e-beTlum.  —  The  back  part  of  the  brain.     See  Fig.  65. 
5&r'e-brum.  — The  highest  and  largest  part  of  the  brain.     See  Fig.  65. 
chest,  or  tho'rax. — The  cavity  within  the  ribs,  which  holds  the  lungs 

and  heart.     See  Fig.  38. 

ch5'roid.  —  The  middle  coat  of  the  eyeball.     See  Fig.  75. 
chyle.  — The  food  in  the  intestine,  after  it  is  thoroughly  digested, 
chyme.  — The  food  mass  as  it  leaves  the  stomach, 
clav'i-cle.  —The  collar  bone.     See  Fig.  42. 
co-ag'u-la'tion.  — A  change  from  a  liquid  to  a  solid  condition,  such  as 

that  which  occurs  in  the  white  of  an  egg  when  heated. 
coVcyx.  —  A  small  piece  of  bone  at  the  lower  end  of  the  spinal  column. 
cSm-mu'ni-ca-ble.  —  Capable  of  being  transmitted  from  person  to  per- 
son. 
cfim'pre'ss.  —  A  mass  of  soft  cloth  arranged  with  a  bandage  to  produce 

pressure  upon  any  part. 

cSn-ta'gious.  —  Easily  passed  from  person  to  person. 
c5n-tr5c'tion.  —  Shortening. 

cSn'vo-lu'tions.  —  The  folds  in  the  surface  of  the  brain, 
cords.  —  See  tendons. 
c6rn.  — A  thickened  portion  of  the  epidermis  (usually  on  a  toe)  caused 

by  friction  or  pressure, 
cor'ne-a".  —  The  transparent  covering  of  the  eyeball,  in  front.     See  Fig. 

76. 


GLOSSARY  OF   TECHNICAL   TERMS  335 

coVpiis-Qle.  —  A  small  body. 

cra'ni-um.  —  The  rounded  part  of  the  skull,  containing  the  brain.  See 
Fig.  44. 

der'mis.  —The  inner  layer  of  the  skin.     See  Fig.  61. 

di'a-phrSgm.  —  A  tough,  muscular  membrane  separating  the  thorax 

and  abdomen.     See  Fig  38. 

diph-the'ri-a.  — A  very  serious  disease  of  the  throat, 
dis'm-fec'tion.  —  Destroying  the  germs  of  disease, 
dis'lo-ca'tion.  — The  wrenching  of  bones  out  of  position, 
dis-tilled'  liq'ufirs.  — Liquors  made  by  separating  the  alcohol  from  a 

fermenting  substance. 
duct.  —  A  slender  tube  by  which  secretions  are  carried  from  a  gland. 

See  Fig.  11. 
d^s-pep'si-a.  — A  disease  of  the  digestive  organs. 

ear'drum.  —  The  middle  cavity  of  the  ear.     See  Fig.  76. 

en-eim'el.  —  The  outer  hard  covering  of  the  teeth. 

ep'1-dem'Ic.  — Any  disease  spreading  among  a  great  number  of  people. 

ep'i-der'mis.  —The  outer  layer  of  the  skin.     See  Fig.  61. 

ep'i-glSt'tis.  —  The  lid  covering  the  opening  into  the  windpipe.  See 
Fig.  12. 

ep'i-the'li-um. —  A  layer  of  cells  covering  the  various  internal  and  ex- 
ternal surfaces  of  the  body.  See  Fig.  12. 

Eu-sta'chi-a'n  tube.  —  A  tube  leading  from  the  upper  part  of  the  throat 
to  the  middle  ear.  See  Figs.  12  and  76. 

ex-cre'tion.  —  Waste  material  passed  from  the  body. 

ex'ha-la'tion.  —  Breathing  air  out  of  the  lungs. 

fat  9ell.  —  A  minute  drop  of  fat  such  as  exists  in  meat.     See  Fig.  2. 
fe'mur.  — The  bone  extending  from  the  hip  to  the  knee.     See  Fig.  42. 
fer'men-ta'tion. — A  change  occurring  in   sugar  solutions  by  which 

alcohol  is  produced. 

fer-men'ted  Hq'u5rs.  — Drinks  made  from  simple  fermented  material, 
fi'bers.  —  Minute  threads,  like  those  of  muscles  or  nerves, 
flushed.  —  Red  from  the  expansion  of  blood  vessels. 
fo-ra'men  6-va'le. — The  opening  from  the  middle  ear  into  the  inner 

ear.     See  Fig.  76. 

frQnt'al  bone.  —  The  bone  forming  the  forehead.     See  Fig.  44. 
fu'el  foods.  —  Foods  used  to  develop  force  or  heat, 
fu'mi-ga'tion.  — Treating  with  fumes  of  gas,  usually  to  destroy  disease 

germs. 


336  PHYSIOLOGY  AND   HYGIENE 

gall-bl&d'dgr.  —  A  sac  which  collects  the  bile  secreted  by  the  liver. 

See  Fig.  13. 
gan'gli-fln. —  A  mass  of  nerve  tissue  containing  nerve  cells.     See  Fig. 

67. 
gas'tric  jui^e.  —  The  digestive  fluid   secreted  by  the  glands  of  the 

stomach, 
glbt'tis.  —  The  opening  from  the  throat  into  the  windpipe.     See  Fig. 

12. 
glu'cose,  or  grape  sugar.  —  Sugar  found,  or  similar  to  that  found,  in 

fruits. 

glu'ten.  —  A  proteid  derived  from  wheat  and  some  other  substances, 
grav'i-ty.  —  The  force  that  pulls  objects  toward  the  earth, 
gris'tle.  —  The  name  given  to  cartilage  when  cooked,  as  in  meat, 
gul'let.  —  See  oesophagus. 

hae'mS-glo'bm.  — The  red  coloring  matter  in  blood. 

hair  fol'li-cles.  —  The  little  pockets  from  which  hairs  grow.     See  Fig. 

62. 

hard  water.  —  Water  containing  some  mineral  substance,  usually  lime. 
hem'i-spheres.  —  The  two  halves  of  the  cerebrum.     See  Fig.  66. 
hi'ber-nat'ing.  — Remaining  in  a  dormant,  sleeping  condition  during 

the  winter  months. 
hinge  joint.  —  A  joint  in  which  the  bones  can  move  in  one  direction 

only.     See  Fig.  62. 
hu'mer-us.  —  The  bone  extending  from  the  shoulder  to  the  elbow.     See 

Fig.  42. 

il'i-um.  —  One  of  the  bones  of  the  pelvic  girdle.     See  Fig.  42. 

Im-mu'ni-ty\  —  Ability  to  resist  disease. 

In-$i'sors.  —  The  eight  middle  front  teeth.     See  Fig.  9. 

in'cus.  —  One  of  the  bones  of  the  ear.     See  Fig.  76. 

in'di-ges'tion.  —  Inability  properly  to  digest  food. 

In-f  ec'tious.  —  Produced  by  germs,  usually  contagious. 

m'flam-ma'tion.  —  A  condition  of  enlarged  blood  vessels,  accompanied 

by  heat  and  soreness  in  the  inflamed  part. 
in'hal-a'tion.  —  Breathing  air  into  the  lungs. 
in-5c'u-late.  —  To  introduce  infectious  matter, 
m-tes'tme.  — The  tube  through  which  food  passes  after  leaving  the 

stomach.     See  Fig.  13. 

in-vbl'un-ta"-ry\  —  Without  the  exercise  of  will  power. 
I'ris.  —  The  colored  membrane  around  the  pupil  of  the  eye. 


GLOSSARY  OF  TECHNICAL   TERMS  337 

is'chi-um.  — One  of  the  bones  of  the  pelvis.     See  Fig.  42. 
i'so-la'tion.  —  Keeping  a  patient  away  from  other  persons  to  prevent 
his  giving  them  disease. 

kid'neys.  —  The  organs  for  removing  the  waste  products  found  in  the 
urine.  See  Fig.  60. 

lach'ry-mal  duct.  —  The  duct  which  carries  tears  from  the  eyes  to  the 
nasal  cavities.  See  Fig.  72. 

lach'ry-mal  gland.  —  The  gland  that  secretes  the  tears. 

lac'te-als.  —  Small  tubes  that  carry  fat  from  the  intestines  to  the  blood 
vessels.  See  Fig.  16. 

lar'ynx,  or  Ad'anVs  Sp'ple.  —  An  enlarged  part  of  the  windpipe  con- 
taining the  vocal  cords.  See  Fig.  12. 

lig'a-ments.  — Bands  of  white  connective  substance,  which  join  bones. 
See  Figs.  51  and  52. 

lig'a-ture.  — A  band  drawn  tightly  around  some  part  of  the  body  to 
stop  bleeding.  See  Fig.  30. 

lime.  —  A  mineral  substance  for  making  bone. 

Hv'er.  — A  large  red  gland  lying  near  the  stomach.     See  Fig.  13. 

lungs.  —  Two  organs  in  the  chest  cavity  which  absorb  oxygen  and  give 
off  carbon  dioxide. 

lymph  ves'sel.  —A  minute  tube  that  carries  lymph. 

ma-la'ri-a.  — A  disease  accompanied  by  chills  and  fever. 

mal'le-us.  —  One  of  the  bones  of  the  ear.     See  Fig.  76. 

man'di-ble.  —  The  jaw  bone.     See  Fig.  44. 

mar'row.  —  A  fatty  material  in  the  middle  of  the  long  bones.     See  Fig. 

45. 

mas'ti-cate.  —  To  chew. 

me-dul'la.  —The  lowest  part  of  the  brain.     See  Fig.  65. 
med'ul-la-ry  sheath.  — The  covering  of  the  axis  cylinder  of  a  nerve. 

See  Fig.  67. 
mem'brane.  —  Soft  tissue  in  the  form  of  a  sheet  or  a  layer  covering 

some  part  of  the  body, 
mes'en-te-ry.  — A  membrane  wrapped  around  the  intestine  and  filled 

with  blood  vessels.     See  Fig.  16. 
met'a-car'pals.  —  The  bones  between  the  wrist  and  the  fingers.     See 

Fig.  42. 
m£t'a-tar'sais.  —  The  bones  between  the  ankle  and  the  toes.     See  Fig. 

42. 


338  PHYSIOLOGY   AND   HYGIENE 

mo'lars.  —  The  large  back  teeth,  twelve  in  number.     See  Fig.  9. 
mumps.  —  A  disease  accompanied  by  swollen  jaws  and  cheeks. 
mus'gle  fi'bers.  —  The  microscopic  threads  of  which  muscle  is  made. 

See  Fig.  58. 
my'o-sln.  —  A  proteid  found  in  meat. 

nar-ctffic.  —  A  drug  that  dulls  body  action. 

na'sal.  —  Pertaining  to  the  nose. 

nerve  cells.  —  Minute  bodies  at  the  ends  of  nerve  fibers  which  cause 

and  receive  stimuli.     See  Fig.  69. 
nerve  fi'bers.  —  The  microscopic  threads  of  which  a  nerve  is  composed. 

See  Fig.  68. 

nerves.  —  Long  bundles  of  fibers  that  carry  messages  in  the  body. 
neu'trS-lize.  —  To  counteract  or  destroy  the  effect  of. 
ni-tr5g'e-nous.  —  Foods  containing  nitrogen. 
nu-tri'tious.  —  Capable  of  building  up  the  body  or  furnishing  it  with 

heat  or  force. 

8c-0'pl-til.  —  The  bone  forming  the  back  of  the  skull.     See  Fig.  44. 
(B-s5ph'a-gus,  or  gul'ISt.  —  A  tube  extending  from  the  throat  to  the 

stomach.    See  Fig.  13. 

5x'I-da'tion.  —  A  union  of  some  substance  with  oxygen. 
n.  —  A  gas  forming  one  fifth  of  the  air. 


pSl'dte.  —  The  roof  of  the  mouth. 

pSn'cre-£s.  —  A  large  gland  which  secretes  a  fluid  to  digest  proteids, 

starches,  and  fats.    See  Fig.  13. 
pap-il'la.  —  A  minute,  finger-like  projection. 
paVa-site.  —  An  animal  or  plant  that  lives  on  the  body  of  another  ani- 

mal or  plant. 

pa-ri'e-t&ls.  —  The  bones  forming  the  sides  of  the  cranium.    See  Fig.  44. 
par  5t'id  glands.  —  The  salivary  glands  in  front  of  the  ear. 
pa-tel'la.  —  The  round  bone  in  front  of  the  knee.     See  Fig.  42. 
pel'vis,  or  pel  'vie  gir'dle.  —  The  hip  bone.     See  Figs.  38  and  42. 
pe'trous  bone.  —  The  very  hard  bone  that  contains  the  ear. 
pha-lan'ges.  —  A  name  given  to  the  bones  of  the  fingers  and  toes. 
phlggm.  —  A  thick,  jelly-like  material  secreted  by  the  air  passages  or 

the  stomach. 
pil'lars  of  the  fau'ces  —  Two  curtain-like  sheets  between  the  mouth 

and  the  throat.     See  Fig.  10. 
plas'ma.  —  The  liquid  part  of  the  blood. 


GLOSSARY  OF  TECHNICAL  TERMS  339 

pneu-m5'ni-a.  —  A  very  serious  disease  of  the  lungs. 

pdres.  —  Small  openings  in  the  skin  through  which  the  sweat  passes. 

pfls-te'rior  root.  —  The  branch  of  the  spinal  nerves  which  carries  mes- 
sages from  the  skin  and  muscles  to  the  brain. 

pre-ser'va-tives.  —  Chemical  substances  added  to  food  materials  to  pre- 
vent their  spoiling. 

pro'te-ids.  — Foods  useful  for  building  body  tissue,  such  as  albumen, 
gluten,  etc. 

pu'bis.  —  One  of  the  bones  of  the  pelvic  girdle.     See  Fig.  42. 

pul'mo-na-ry'  ar'te-ry.  — The  artery  which  carries  blood  from  the  heart 
to  the  lungs.  See  Fig.  23. 

pul'mo-na-ry  cir-cu-la'tion. —  The  circulation  of  the  blood  from  the 
heart  to  the  lungs  and  back. 

pulse.  — A  wave  of  pressure  that  passes  along  the  arteries  with  each 
heart  beat. 

pu'pil.  —  The  circular  opening  in  the  front  of  the  eye  that  allows  light 
to  pass  into  the  eye. 

rab'id.  —  Suffering  from  rabies,  or  hydrophobia. 

ra'di-us.  — One  of  the  bones  of  the  forearm.     See  Fig.  42. 

re 'flex  ac'tions.  — Actions  that  take  place  without  the  exercise  of  the 

will. 

ren'net.  — A  ferment  secreted  by  the  stomach,  which  curdles  milk, 
res'pi-ra'tion.  —  The  absorption  of  oxygen  and  elimination  of  carbon 

dioxide  by  the  lungs. 
rSt'i-na.  — The  sensitive  surface  at  the  back  of  the  eye.     See  Fig.  75. 

sa'crum.  — The  part  of  the  spinal  column  between  the  hips. 

sa-li'va.  — The  secretion  that  moistens  the  mouth. 

sSl'i-va-ry  glands.  —The  glands  that  secrete  saliva.     See  Fig.  11. 

scap'u-la.  —The  bone  of  the  shoulder  blade.     See  Fig.  42. 

scar'let  fe'ver.  — A  disease  characterized  by  a  pinkish  eruption  of  the 

skin. 

scle-rb't'ic.  —  The  outer  coat  of  the  eyeball.     See  Fig.  75. 
se-cre'tion.  —  Material  produced  by  a  gland  for  the  use  of  the  body, 
s&m'i-lu'nar  valves.  — Three  valves  in  the  large  arteries  near  the  heart. 
sSn'so-rY  nerves.  —  Nerves  that  carry  messages  to  the  brain  resulting 

in  sensations. 
spi'nal  c6rd.  — The  part  of  the  nervous  system  which  extends  down 

within  the  backbone.     See  Figs.  43  and  66. 
spl'nal  nerves.  —  Nerves  arising  from  the  spinal  cord. 


340  PHYSIOLOGY  AND   HYGIENE 

spine.  — The  name  given  to  the  backbone. 

spleen.  —  A  good-sized  gland  in  the  abdomen.     See  Fig.  13. 

sprain.  — The  tearing  or  straining  of  ligaments  at  a  joint. 

spu'tum.  —  Matter  spit  up  from  the  throat  or  lungs. 

sta'pes.  —  One  of  the  bones  of  the  ear.     See  Fig.  76. 

starch  grains.  — The  minute  bits  of  starch  as  they  are  found  in  the 

potato  and  other  raw  foods. 
ster'i-liz-ing.  —  Heating  a  substance  until  all  living  organisms  (bacteria) 

are  killed. 

ster'num.  —The  breastbone.     See  Fig.  42. 

stim'u-lus.  — A  shock  that  causes  a  muscle  or  other  organ  to  act. 
suf  fd-ca'tion.  — Stopping  of  breathing  by  closing  the  windpipe  or  by 

some  other  means. 
sys-tem'Ic  ^Ir'cu-la'tion.  —  The  circulation  in  all  of  the  body  except 

the  lungs. 

tar 'sals.  —  The  ankle  bones.     See  Fig.  42. 

taste  buds.  —  The  organs  of  taste  in  the  tongue. 

ten'dflns.  —  Bands  of  white  substance  uniting  muscles  with  bones.    See 

Fig.  56. 

tho'r&x.  —  The  chest, 
throat.  —  The  cavity  at  the  back  of  the  mouth  into  which  the  mouth 

and  nose  open.     See  Fig.  12. 
tib'I-a.  — The  large  bone  extending  from  the  knee  to  the  ankle.    See 

Fig.  42. 

tfin'sils.  — Two  rounded  bodies  at  the  back  of  the  mouth.    See  Fig.  10. 
tfln-si-li'tis.  —  A  disease  of  the  throat,  accompanied  by  sore  throat  and 

fever. 

tSx'm.  — A  poison  produced  by  a  germ, 
tra'che-a.—  The  windpipe. 

tym-pan'Ic  c&v'i-ty.  — The  ear  drum  or  middle  ear. 
tym-pan'ic  mem'brane.  —  A  membrane  stretched  across  the  passage 

leading  to  the  ear.    See  Fig.  76. 

ul'na.  — One  of  the  bones  of  the  forearm.     See  Fig.  42. 

u're-a.  — The  chief  waste  product  of  muscle  action,  secreted  by  the 

kidneys. 
u-re'tSr.  —  The  duct  leading  from  the  kidney  to  the  bladder.     See 

Fig.  60. 
u'vu-la.  —  A  small  piece  of  the  soft  palate  hanging  downward  from  the 

back  of  the  mouth.     See  Fig.  10. 


GLOSSARY  OF  TECHNICAL   TERMS  341 

vac'ci-na'tion.  —  Treatment  designed  to  prevent  smallpox. 

valve.  —  A  mechanism  to  open  and  close  a  passage. 

va'so-mo'tor  nerves.  —  Nerves  controlling  the  size  of  the  small  blood 

vessels. 

vein.  —  A  blood  vessel  carrying  blood  toward  the  heart, 
ve'notis  blood.  —  Blood  made  impure  by  gathering  up  the  wastes  of  the 

body, 
ven'tri-cles.  —  The  chambers  of  the  heart  that  send  blood  into  the 

arteries.     See  Fig.  23. 
ver'mi-form  ap-pen'dlx.  —  A  small  projection  from  the  end  of  the  large 

intestine.     See  Fig.  13. 

ver'te-bra. —  One  of  the  bones  composing  the  spine.    See  Fig.  43. 
vil'H. —  Little  projections  on  the  inside  of  the  intestine  for  absorbing 

food.     See  Fig.  17. 
vit're-ous  hu'mSr.  —  One  of  the  transparent  media  of  the  eye.     See 

Fig.  75. 
vo'cal  c6rds.  —  Two  membranes  in  the  larynx  whose  vibrations  produce 

the  voice. 

yeast.  —  Microscopic  plants  that  cause  the  fermentation  of  sugar. 


INDEX 


Abdominal    muscles,    Exercises 

for,  328. 

Abscesses,  240,  269. 
Acid  poisons,  314. 
Adulterated  foods,  296. 
Air,   as   a   distributor   of   bac- 
teria, 244,  295. 

Need  of  fresh,  117,283. 

passages,  105. 

sacs,  108. 
Albumen,  14. 
Alcohol,  27,  100,  184. 

and  consumption,  287. 

Appetite  for,  70,  186. 

Use  of,  30,  69,  86,  101,  184, 

246-249,  332. 
Ale,  29. 

Animal  tuberculosis,  290. 
Antidotes  to  poisons,  313. 
Antitoxin,  257. 
Appetite  as  a  guide,  68. 
Arms,  Exercises  for,  326. 
Arsenic  poisoning,  314. 
Arteries,  83,  87,  91. 

Location  of,  89. 
Artery,  Pulmonary,  84. 
Artificial  breathing,  121. 
Auditory  nerve,  224. 
Auricles,  83. 

Back,  Exercises  for,  327. 

Backbone,  126,  133. 

Bacteria,  25,  163,  239,  279,  291. 

how  carried,  243,  293,  295. 

how  they  get  out  of  the 
body,  242,  280. 

Protection     against,     240, 

252,  281,  285,  292. 
Baking,  77. 

powder,  78. 

Balance  of  the  body,  321. 
Ball-and-socket  joints,  138,  139. 
Bananas,  23. 


Bar  and  Ring  exercise,  327. 
Baseball,  as  exercise,  330. 
Baths,  172,  237. 

Cold,  172. 

Hot,  175. 
Beans,  23. 
Beef  tea,  74. 
Beer,  29. 
Beets,  23. 

Biceps  muscle,  141. 
Bicuspid  teeth,  38. 
Bile,  54. 

Bites  of  animals,  273,  308. 
Bladder,  156. 
Bleeding,  90. 

how  stopped,  91. 
Blisters,  158. 
Blood,  80. 

Circulation  of,  80. 

Clotting  of,  93. 

Impure,  89. 

poisoning,  269. 

Pure,  89. 

Respiratory  changes  in,  113. 
Blood  vessels,  87. 

of  lungs,  108. 

of  skin,  100,  162. 

Regulation  of,  97,  191,  203. 
Blushing,  99. 
Boards  of  Health,  291. 
Body,  Development  of  the,  316. 

Dangers  of  unequal,   318. 

Importance  of,  317. 

Results  of,  333. 
Boiling,  57,  76,  295. 
Boils,  240,  269. 
Bones,  124,  128. 

Broken,  132,  237. 

Carpal,  125. 

how  held  together,  136. 

List  of,  152. 

Material  for,  18,  128. 

Misshapen,  130. 


342 


INDEX 


343 


Bones  —  continued. 

of  children,  129. 

Structure  of,  128. 
Bowels,  53. 

Brain,  96,  99,  145, 166, 189, 190. 
Brandy,  30. 
Bread  raising,  78. 
Breastbone  (see  Sternum). 
Breathing,  110. 

and  exercise,  115. 

Artificial,  121. 

Center  ol  191,  202,  203. 

Exercises  for,  U2Ji2 1 . 

Process  of,  32lT~" 

Purpose  of,  113,  318,  322. 

througlTmputh,  105,  318. 
Broiling,  57,  7&> 
Bronchus,  107. 
Burns,  Treatment  of,  177. 
Butter,  17,  19. 

Callosities,  158. 
Candy,  67,  229. 
Canine  teeth,  38. 
Capillaries,  87,  88. 

of  lungs,  108. 

of  muscles,  153. 
Carbolic  acid,  303,  314. 
Carbon  dioxide,  104,  113,  115. 
Carpal  bones,  125,  152. 
Cartilage,  133. 
Casein,  14. 
Cereals,  21,  67. 
Cerebellum,  191. 

Duties  of  the,  203. 
Cerebrum,  191. 

Duties  of  the,  204. 

Hemispheres  of  the,  192. 
Character,  and  physical  train- 
ing, 300. 
Cheeks,  37. 
Cheese,  19. 
Chest,  109,  327. 
Chicken  pox,  241. 
Chilblains,  179. 
Chills  and  fever,  239. 
Chloral,  182. 
Chloride  of  lime,  302. 
Chocolate,  27,  67. 
Choking,  306. 


Cholera,  263. 

Cholera  mixture,  314. 

Chyle,  56. 

Chyme,  51. 

Cider,  29. 

Cigarettes,  183. 

Circulation  of  blood,  80,  89. 

Clavicle,  125,  152. 

Cleanliness,  172. 

Clothing,  176. 

Clotting  of  blood,  93. 

Cocaine,  182. 

Cocoanuts,  23. 

Coffee,  26. 

Cold,  Sensation  of,  99,  233. 

Taking,  117, 169. 
Cold-blooded  animals,  166. 
Colds,  117,  169,  237. 
Color  blindness,  220. 
Concentration  of  thought,  208. 
Consumption,  or    tuberculosis, 

20,  117,  277. 
Consumptives,  Precautions  for, 

287. 
Contagious  diseases,  238,  242. 

Immunity  from,  241. 

Prevention  of,  242. 

Spread  of,  300. 
Cooking,  Purpose  of,  72. 

Methods  of,  76. 

Principles  of,  74. 
Cords,  137,  141. 
Corn,  21,  22,  28. 
Corns,  158. 
Corpuscles  of  blood,  red,   81 ; 

white,  82. 

Corrosive  sublimate,  302,  314. 
Cottonseed  oil,  17. 
Coughing,  45,  202,  244,  246. 
Cramps,  307. 
Cuts,  Treatment  of,  163,  272. 

Deafness,  224,  226. 
Dermis,  157,  162. 
Diaphragm,  110. 
Digestibility  of  foods,  56. 
Digestion,  37,  49. 

in  the  intestines,  55. 

in  the  mouth,  43. 

in  the  stomach,  49. 


344 


INDEX 


Diphtheria,  20,  240,  257,  300. 
Direction  of  sound,  how  judged, 

225. 
Diseases,  238. 

Contagious,  238,  253. 
Distribution   of,    20,   293, 

295,  297,  300. 
Germs,  source,  255. 
Immunity  from,  241. 
Parasitic,  238. 
Disinfection,  301,  304. 
Dislocation  of  joints,  140. 
Distance  of  sound,  how  judged, 

225. 

Distilled  liquors,  29. 
Dogwood  poisoning,  310. 
Drowning,   Treatment  in   case 

of,  120. 
Dumb-bells,  327. 

Ear  bones,  224. 

drum  (see  Tympanic     cav- 
ity). 

Middle,  222. 
Ears,  222. 

Care  of,  225. 
Ease  of  motion,  325. 
Eating,  Pleasure  in,  68. 

Time  of,  66. 
Eggs,  21, 67. 

Electricity,  Accidents  from,  311. 
Emergencies,  305. 
Epidermis,  157. 

Thickened  parts  of,  158. 
Epiglottis,  44,  45,  106. 
Epithelium,  60. 
Erysipelas,  269. 
Eustachian  tube,  44,  222. 
Excretions,  154. 
Exercise,  Need  of,  148,  317. 
Exercises,   for   breathing,    11%, 
321. 

for  development  of  various 

muscles,  326. 
Eye,  217. 
Eyeball,  214,  216. 

Size  of,  214. 
Eyelashes,  215. 
Eyelids,  215. 
Eyes,  Care  of,  220. 


Fainting,  95. 
Fat,  17,  153. 

Absorption  of,  61. 

cells,  17,  157. 

Digestion  of,  56. 
Feeling,  231. 
Femur,  125,  134,  152. 
Fermentation,  27. 
Fermented  liquors,  29. 
Fever,  Scarlet,  20,  240,  241. 

Typhoid,  20,  240,  260,  275, 
393. 

Yellow,  241. 
Filtering,  295. 
Finger  nails,  161. 
Flavor,  Use  of,  26. 

produced  by  bacteria,  240. 

produced  by  cooking,  72. 
Flies  as  disease  distributors,  267. 
Flour,  21. 
Fly  powders,  314. 
Food,  Absorption  of,  58-62. 

Amount  of,  needed,  31. 

habits,  65. 

Kind  of,  13. 

Mastication  of,  42. 

Purposes  of,  11. 

Uncooked,  as  a  distributor 
of  disease,  245. 

values,  32. 

value  tables,  33,  34,  35. 
Foods,  Adulteration  of,  296. 

Cost  of,  32,  66. 

Digestibility  of,  56. 

for  building  purposes,   12, 
19    32 

for  fuel,  13,  15,  19,  153. 

Inspection  of,  292,  296. 

Preservatives  used  in,  297. 

Source  of,  18. 

Undigested  portions  of,  62. 
Formalin,  302. 

Frostbites,  Treatment  of,  178. 
Fruits,  23,  67. 
Frying,  58,  78. 
Fumigation,  304. 

Gall  bladder,  47,  54. 
Games  and  sports,  317,  330. 
Ganglion,  193. 


INDEX 


345 


Garbage,  297. 
Gastric  juice,  49. 
Germs  (see  Bacteria). 
Gin,  30. 
Glands,  155. 

Ducts  of,  42. 

Gastric,  48,  155. 

Lachrymal,  214. 

of  tongue,  227. 

Pancreatic,  54. 

Salivary,  41,  155. 

Sweat,  157,  163,  169. 

Tear,  215. 
Glottis,  44,  45. 
Gluten,  14. 
Graham  meal,  21. 
Grape  juice,  29. 

Gravity,  Effect  of,  on  circula- 
tion, 95. 
Grip,  259. 
GuUet,  45. 

Habits,  Acquiring  of,  205. 
Hair,  159. 

Follicle  of,  159. 
Hammer  throwing,  331. 
Hands,  Exercises  for,  328. 
Health,  Disease  and,  237. 

Duty  of  preserving,  249. 

Boards  of,  292. 
Hearing,  Sense  of,  222,  224. 
Heart,  82. 

Beating  of,  85. 

Center  of  control  of,    191, 
203. 

Regulation  of,  96. 

Valves  of  the,  85. 
Heat  prostration,  312. 
Hemoglobin,  82. 
Hibernating  animals,  167. 
Hinge  joints,  134,  137. 
Hookworm,  262. 
Hospitals,  304. 
Humerus,  125,  138. 
Hunger,  68,  231. 
Hydrophobia,  273. 
Hygiene,  Personal  and  Public, 
291. 

Immunity,  275. 


Incisors,  38. 
Incus,  222. 
Indian  meal,  21. 
Indoor  life,  Evils  of,  117. 
Inflammation,  269. 
Influenza,  259. 

Insects  as   distributors    of  dis- 
ease, 245. 
Inspection,  292. 

of  food,  296. 

of  ventilation,  295. 

of  water,  293. 
Inspiration,  111. 
Intemperance,  72,  250. 
Intestines,  47,  53. 
Involuntary  muscles,  143,  145. 
Isolation,  300. 
Ivy  poisoning,  309. 

Japanese,  The,  and  preventable 

diseases,  254. 
Joints,  134. 

Ball-and-socket,  138. 

Dislocation  of,  140. 

Hinge,  134,  137. 

Injuries  at,  139. 

Knee,  134. 

Shoulder,  138. 
Jumping,  330. 

Kidneys,  155. 

Tubules  of  the,  156. 

Lachrymal  duct,  214. 

gland,  214. 
Lacteals,  62. 
Lard,  17. 

Larynx,  44,  106,  107,  133. 
Laudanum,  181,  314. 
Lead  poisoning,  314. 
Legs,  Exercises  for,  329. 
Lens  of  eye,  217. 
Lentils,  23. 

Ligaments,  135,  136,  139. 
Lime,  18,  26. 
Liquors,  Distilled,  29. 

Fermented,  29. 
Liver,  53. 

Duties  of  the,  54. 
Lockjaw,  271. 


346 


INDEX 


Lung  diseases  associated  with 

impure  air,  117. 
Lungs,  106. 

Capacity  of,  111. 

Exercise  of,  112. 
Lymph  vessels,  62. 

Malaria,  239,  264. 

Malleus,  222. 

Malt,  28. 

Meals,  Frequency  of,  66. 

Measles,  240,  268,  300. 

Meats,  20. 

Cooking  of,  73. 
Digestion  of,  49. 
Medicines,  237. 
Medulla  oblongata,  191. 
Duties  of  the,  202. 
Mercury  poisoning,  314. 
Mesentery,  58. 
Metacarpals,  125,  152. 
Metatarsals,  125,  152. 
Middle  ear,  222. 
Milk,  19. 

Curdling  of,  51. 

Digestion  of,  51. 

Diseases  distributed  by,  20, 

261. 

Inspection  of,  292. 
Mind,  Dependence  of,  on  body, 

210. 

Care  of  the,  207. 
Mineral  substances,  26. 
Molar  teeth,  38. 
Molasses,  28. 
Morphine,  181. 
Mosquito   bites,   the    cause   ol 

malaria,  239,  264. 
Motor  centers,  Location  of,  206 

207. 

nerve  fibers,  200. 
Mouth,  37. 

-breathing,  105. 
Mumps,  240,  241,  259,  300. 
Muriatic  acid  poisoning,  314. 
Muscle,  Biceps,  141. 
fibers,  142. 
sense,  235. 
Muscles,  141. 

at  joints,  137,  139. 


VCuscles  —  continued. 

Contraction  of,  144,  145. 

Developing  of,  317. 

Growth  of  the,  147. 

Involuntary,  143,  145. 

Number  of,  146. 

of  blood  vessels,  97. 

of  breathing,  109. 

of  eye,  216. 

Structure  of,  141. 
Vlyosin,  14. 

Vails  of  fingers  and  toes,  161. 
Narcotics,  180. 

Effect  of,  upon  mind,  210. 
Nasal  cavities,  41,  44,  230. 
STearsightedness,  219. 
Sleek,  Exercises  for,  328. 
STerve  cells,  195. 

fibers,  145,  194. 

trunks,  194. 
Nerves,  96,  190,  194. 

Anterior  root  of  the,  194. 

Duties  of  the,  198. 

Motor,  200. 

of  hearing,  224. 

of  muscles,  145. 

of  nose,  230. 

of  retina,  218. 

of  skin,  157,  162. 

of  tongue,  227. 

Posterior  root  of,  194 

Sensory,  200. 

Vaso-motor,  99. 
Nervous  system,  189. 
Night  air,  118. 
Nitric  acid  poisoning,  314. 
Nitrogenous  foods,  14. 
Nosebleed,  306. 
Nuts,  23. 

Oatmeal,  21,  67. 
Oats,  21,  22. 
(Esophagus,  44,  45. 
Oil  glands,  160. 
Olfactory  nerve,  230. 
Olive  oil,  17. 
Opium,  181,  314. 
Optic  nerve,  216,  218. 
Organic  matter,  18. 
Overindulgence,  72,  250. 


INDEX 


347 


Oxalic  acid  poisoning,  314. 

Oxidation,  104,  153. 

Oxygen,  13,  104,  113,  115,  116, 

318. 

Use  of,  114. 
Oysters,  as  disease  distributors, 

262. 

Pain  sense,  234. 
Palate,  37,  44. 
Pancreas,  47,  54,  155. 
Papillae  of  hair,  159. 

of  tongue,  227. 
Paragoric,  181,  314. 
Parasites,  73. 
Parasitic  animals,  239. 

bacteria,  239. 

diseases,  238. 
Paris  green,  314. 
Peanuts,  23. 
Peas,  23. 

Pelvic  girdle,  125. 
Phosphorus,  315. 
Physical    training     (see    Body, 

Development  of). 
Piano,  Learning  to  play  the,  203. 
Pink  eye,  274. 
Plague,  267. 

Plumbing,  Importance  of,  243. 
Pneumonia,  117,  260. 
Poise,  320. 

Poisoning,  Treatment  for,  313. 
Pores  of  skin,  164. 
Position  in  sitting,  319. 

in  standing,  287,  320. 

in  walking,  324. 
Potatoes,  23,  32. 

Cooking  9f,  73. 
Preservatives  in  foods,  297. 
Pressure,  Sense  of,  231. 
Preventable  diseases,  252. 
Proteids,  14,  153. 

Absorption  of,  61. 

coagulated  by  heat,  74. 

Digestion  of,  50,  55. 

Need  of,  50,  55. 

Source  of,  33,  34,  35. 
Pulmonary  artery,  84. 
Pulse,  86. 
Pupil  of  the  eye,  217. 


Quarantine  (see  Isolation). 

Rabies,  273. 

Radius,  125,  152. 

Recreation,  209. 

Reflex  action  in  spinal  cord,  201. 

in  medulla,  202. 
Rennet,  51. 
Repair  of  body,  12. 
Reservoirs,  Care  of,  294. 
Respiration,  105,  115. 

Restoration  of,  120. 
Retina,  217. 

Ribs,  125,  127,  133,  152. 
Rice,  21,  22. 
Roasting,  57,  77. 
Rubbing,  174,  237. 
Rum,  30. 
Running,  330. 
Rye,  21. 

Saliva,  Use  of,  41,  43. 

Salivary  glands,  41,  155. 

Salt,  26. 

Sauces,  229. 

Scapula,  125,  138,  152. 

Scarlet  fever,  20,  240,  241,  268, 

300. 

Secretions,  154. 
Sensations,  213. 

Location  of,  in  brain,  199, 

207. 

Sense  organs,  214. 
Senses,  213,  231. 
Sensory  nerve  fibers,  200. 
Sewage,  243,  294,  297. 
Sewerage  systems,  299. 
Shoes,  131. 
Shot  putting,  332. 
Shoulder  joint,  138. 
Shoulders,  Exercises  for,  327. 
Sick  room,  Care  of,  303. 
Sight,  Sense  of,  214. 
Sitting,  Importance  of  correct, 

319. 

Skating,  331. 
Skeleton,  124,  125. 
Skin,  156. 

Care  of,  172. 

Functions  of,  163. 


348 


INDEX 


Skin  —  continued. 

Sensations  of,  231. 

Structure  of,  156. 
Skull,  127. 
Sleep,  207. 

Smallpox,  241,  268,  300. 
Smell,  Sense  of,  214,  229. 

Duration  of,  231. 

Location  of,  230. 

Use  of,  230. 

Snake  bites,  Treatment  of,  308. 
Soothing  sirup,  181,  314. 
Sore  throat,  46. 

Sound,  Direction  of,  how  judged, 
225. 

Distance  of,  how  judged, 

225.     (See  Hearing.) 
Soups,  75. 
Special  senses,  214. 
Spinal  cord,  126, 192,  201. 

Duties  of,  200, 

Gray  matter  of,  193. 

White  matter  of,  193. 
Spine  (see  Backbone). 
Spitting,  Dangers  of,  280. 
Sports  and  games,  329. 
Sprain,  140. 
Sputum,  280. 
Standing,   Correct  position  in, 

320. 

Stapes,  222. 
Starch,  15. 

Absorption  of,  61. 

Digestion  of,  43,  55. 
State  Board  of  Health,  292. 
Sternum,  125,  127. 
Stews,  75. 

Stimulants,  149,  180. 
Stimulus,  145. 
Stings,  Treatment  of,  307. 
Stomach,  Structure  of,  46. 

Digestion  in,  49. 
Strychnine  poisoning,  315. 
Sugar,  16,  28,  153. 

Absorption  of,  61. 
Sulphuric  acid  poisoning,  314. 
Sunstroke,  312. 
Suppleness,  Exercises  for,  325. 
Swallowing,  46. 

Center  of,  191,  203. 


Sweat,  163. 

glands,  157,  163,  169. 
Sweating  as  a  heat    regulator, 

168. 
Swimming,  330. 

Taking  cold,  117,  169. 
Tallow,  17. 
Tapeworm,  239. 
Tarsal  bones,  125,  152. 
Taste,  214,  226. 

buds,  227. 

Confusion  of,   with   smell, 
228. 

Duration  of,  228. 
Tastes,  Different  kinds  of,   227. 
Tea,  26. 

Tear  glands,  215. 
Teeth,  37,  38. 

Care  of  the,  39. 

Growth  of,  38. 

Milk,  38. 

Permanent,  38. 
Temperature  of  body,  13,  167. 

Regulation  of,  165,  168. 

Sense  of,  233. 
Tendon,  137,  141. 
Tennis,  330. 
Tetanus,  271. 
Thinking,  Location  of,  in  brain, 

207. 

Thirst,  68,  231. 
Thorax,  109. 
Throat,  44. 

Sore,  46. 

Tibia,  125,  134,  152. 
Tinfoil  poisoning,  314. 
Tissues,  88. 
Tobacco,  86,  182. 

Use  of,  182. 
Toe  nails,  161. 
Tone,  302,  312. 
Tongue,  37,  44,  226. 
Tonsilitis,  41,  259. 
Tonsils,  40,  44. 
Toothache,  305. 
Touch,  Sense  of,  213,  231. 
Trachea,  45,  106,  107. 
Trachoma,  275. 
Trichina,  239. 


INDEX 


349 


Tuberculosis,    or   consumption, 

20,  117,  277. 
Tubules  of  kidney,  156. 
Tympanic  cavity,  223. 

membrane,  223. 
Typhoid  fever,  20,  240,  260, 293. 

Ulna,  125,  152. 
Urea,  154. 
Ureter,  156. 
Uvula,  37. 

Vaccination,  241. 
Vaso-motor  nerves,  99. 

Center  of,  191. 
Vegetables,  23. 
Veins,  83,  88. 
Venous  blood,  115. 
Ventilation,  116,  118,  295. 
Ventricles,  83. 
Vermiform  appendix,  47. 
Vertebrae,  126. 
Vertebrates,  126. 
Villi,  59. 

Duties  of,  61. 

Structure  of,  60. 
Vocal  cords,  106. 
Vomiting,  47,  313. 

Waist   Muscles,   Exercises  for, 
328. 


Walking,    Correct    method   of, 

324. 

Warm-blooded  animals,  166. 
Warmth,  Feeling  of,  99,  233. 
Warts,  159. 

Waste  products,  54,  63,  153. 
Water,  24,  25. 

Absorption  of,  61. 

Filtering  of,  295. 

Impurities  in,  25,  293,  295. 

Inspection  of,  293. 

Loss    of,    through    lungs, 
114. 

of  lakes,  25. 

of  reservoirs,  25. 

of  rivers,  26,  243. 

of  springs,  25. 

of  wells,  25. 
Water  Commissioners,  292. 
Wheat,  21,  22. 
Whisky,  30. 
Whooping     cough,     240,    274, 

300.     - 

Windpipe,  44,  45,  106. 
Wounds,  Treatment  of,  271. 
Wrists,  Exercises  for,  328. 

Yawning,  Significance  of,  319. 

Yeast,  27,  78. 

Yellow  fever,  241,  265. 


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